V-shaped Cleft Research Articles

The EV71 2A protease occupies the central cleft of SETD3 and disrupts SETD3-actin interaction

SETD3 is an essential host factor for the replication of a variety of enteroviruses that specifically interacts with viral protease 2A. However, the interaction between SETD3 and the 2A protease has not been fully characterized. Here, we use X-ray crystallography and cryo-electron microscopy to determine the structures of SETD3 complexed with the 2A protease of EV71 to 3.5 Å and 3.1 Å resolution, respectively. We find that the 2A protease occupies the V-shaped central cleft of SETD3 through two discrete sites. The relative positions of the two proteins vary in the crystal and cryo-EM structures, showing dynamic binding. A biolayer interferometry assay shows that the EV71 2A protease outcompetes actin for SETD3 binding. We identify key 2A residues involved in SETD3 binding and demonstrate that 2A’s ability to bind SETD3 correlates with EV71 production in cells. Coimmunoprecipitation experiments in EV71 infected and 2A expressing cells indicate that 2A interferes with the SETD3-actin complex, and the disruption of this complex reduces enterovirus replication. Together, these results reveal the molecular mechanism underlying the interplay between SETD3, actin, and viral 2A during virus replication.

Cleft palate in Pierre Robin syndrome: A Review of 7 cases

IntroductionPierre Robin syndrome is a malformative sequence associating retrognathism, glossoptosis and a median cleft palate which is usually large. This poses the problem of its therapeutic management. PurposeTo show the approach of the Stomatology and Maxillofacial Surgery Department of the Mohammed VI University Hospital in the management of cleft palate in Pierre Robin syndrome.This was a retrospective study, covering 5 years, which allowed us to include 7 cases of cleft palate in Pierre Robin syndrome. Our study parameters were epidemiological, clinical, therapeutic and evolutionary. ResultsThe average age of our patients, at the time of the 1st consultation, was 4 months. There was a slight male predominance with a sex ratio = 1.3. The patients presented a U-shaped cleft in 57.1% of cases, and a V-shaped cleft in 42.9% of cases. Three patients underwent a one-stage closure by velopalatoplasty using the Von Langenbeck technique. Four patients underwent a 2-stage closure, i.e., intravascular veloplasty in the first stage, followed by closure of the residual cleft palate in the second stage. The results were satisfactory. A palatal fistula was noted in 42.8% of cases, which was managed secondarily. ConclusionThe management of cleft palate in Pierre Robin syndrome is a real challenge for the maxillofacial surgeon.

Characterization of two 1,3-β-glucan-modifying enzymes from Penicillium sumatraense reveals new insights into 1,3-β-glucan metabolism of fungal saprotrophs

Background1,3-β-glucan is a polysaccharide widely distributed in the cell wall of several phylogenetically distant organisms, such as bacteria, fungi, plants and microalgae. The presence of highly active 1,3-β-glucanases in fungi evokes the biological question on how these organisms can efficiently metabolize exogenous sources of 1,3-β-glucan without incurring in autolysis.ResultsTo elucidate the molecular mechanisms at the basis of 1,3-β-glucan metabolism in fungal saprotrophs, the putative exo-1,3-β-glucanase G9376 and a truncated form of the putative glucan endo-1,3-β-glucosidase (ΔG7048) from Penicillium sumatraense AQ67100 were heterologously expressed in Pichia pastoris and characterized both in terms of activity and structure. G9376 efficiently converted laminarin and 1,3-β-glucan oligomers into glucose by acting as an exo-glycosidase, whereas G7048 displayed a 1,3-β-transglucanase/branching activity toward 1,3-β-glucan oligomers with a degree of polymerization higher than 5, making these oligomers more recalcitrant to the hydrolysis acted by exo-1,3-β-glucanase G9376. The X-ray crystallographic structure of the catalytic domain of G7048, solved at 1.9 Å of resolution, consists of a (β/α)8 TIM-barrel fold characteristic of all the GH17 family members. The catalytic site is in a V-shaped cleft containing the two conserved catalytic glutamic residues. Molecular features compatible with the activity of G7048 as 1,3-β-transglucanase are discussed.ConclusionsThe antagonizing activity between ΔG7048 and G9376 indicates how opportunistic fungi belonging to Penicillium genus can feed on substrates similar for composition and structure to their own cell wall without incurring in a self-deleterious autohydrolysis.

Exploring Anion-π Interactions and Their Applications in Supramolecular Chemistry.

Noncovalent bond interactions provide primary driving forces for supramolecular processes ranging from molecular recognition to self-assembly of sophisticated abiotic and biological machineries. While hydrogen bonding and π-π interactions are arguably textbook concepts playing indispensable parts in various scientific disciplines, noncovalent anion-π interactions have been emerging as attractive forces between π systems and negatively charged species for just about two decades. At the beginning of this century, three research groups reported independently their computational studies on the interactions between anions and aromatic compounds, proposing attractive anion-π interactions. Since π systems such as aromatic rings are traditionally noted as electron rich entities, anions and π systems would be repulsive to each other if there are any interactions. In stark contrast to the acknowledged cation-π interactions, the seemingly counterintuitive noncovalent anion-π bindings invoked great interest in the following years. Although a plethora of calculations had been published, the lack of experimental evidence cast doubt on the existence of anion-π interactions between anions and charge-neutral aromatic systems.During the same time when anion-π interactions were coined, we were studying the chemistry of novel macrocyclic compounds, namely, heteracalixaromatics, and their applications in supramolecular chemistry. It has been shown that heteracalixaromatics are powerful and versatile macrocyclic hosts to bind various guest species forming interesting assembled structures and organometallic complexes. Being a member of heteracalixaromatics, tetraoxacalix[2]arene[2]triaizne adopts a 1,3-alternate conformational structure yielding a V-shaped cavity or cleft formed by two electron-deficient triazine rings. Advantageously, the macrocycle is able to self-tune the cavity sizes by altering the degrees of conjugation between the bridging oxygen atoms with their bonded aromatic rings in response to the guest species in present, rendering it an ideal tool to explore anion-π interactions. We initiated our study on anion-π interactions using tetraoxacalix[2]arene[2]triazine as a molecular tool with the primary aim to clarify experimentally the uncertainty of whether exclusive anion-π interactions exist between anions and charge-neutral aromatic rings. We provided for the first time concrete evidence substantiating the formation of typical anion-π interaction between the anions and 1,3,5-triazine ring and demonstrated subsequently the generality and binding motifs of anion-π interactions. We have then extended our study to anion-π interaction-directed or -driven anion recognition and selective sensing, transmembrane anion transport, molecular self-assembly, and stimuli-responsive aggregation systems. A number of new generation macrocycles and cages constructed from electron-deficient tetrazine and benzenetriimide segments have also been developed in the meantime, advancing the study of anion-π interactions. This Account summarizes our endeavors to explore nascent anion-π interactions and their applications in supramolecular chemistry. We hope this Account will inspire scientists from various disciplines to explore all aspects of the nascent yet fruitful research area of anion-π interactions.

Revision of fossil Metretopodidae (Insecta, Ephemeroptera) in Baltic amber - Part 4: Description of two new species of Siphloplecton Clemens, 1915, with notes on the new S. jaegeri species group and with key to fossil male adults of Siphloplecton.

The Siphloplecton jaegeri species group is established here for three extinct species, namely for the earlier described Siphloplecton jaegeri Demoulin, 1968, and for two new species from Eocene Baltic amber, Siphloplecton landoltisp. nov. and Siphloplecton studemannaesp. nov. Based on the well-preserved specimens of these species, a diagnosis is provided for the newly established species group. Representatives of the S. jaegeri species group are characterized by the presence of large, medially contiguous eyes, stout pointed setae along the outer margin of the foretibia, three intercalaries in the cubital field of the forewing, and elongated penis lobes, which are apically triangular or rounded, medially contiguous, and with a V-shaped cleft apically. Further new specimens of the S. jaegeri species group are documented that cannot be attributed to species level due to their poor preservation. Finally, a key to male adults of fossil species of Siphloplecton is given.

Structure of tRNA methyltransferase complex of Trm7 and Trm734 reveals a novel binding interface for tRNA recognition.

The complex between Trm7 and Trm734 (Trm7–Trm734) from Saccharomyces cerevisiae catalyzes 2′-O-methylation at position 34 in tRNA. We report biochemical and structural studies of the Trm7–Trm734 complex. Purified recombinant Trm7–Trm734 preferentially methylates tRNAPhe transcript variants possessing two of three factors (Cm32, m1G37 and pyrimidine34). Therefore, tRNAPhe, tRNATrp and tRNALeu are specifically methylated by Trm7–Trm734. We have solved the crystal structures of the apo and S-adenosyl-L-methionine bound forms of Trm7–Trm734. Small angle X-ray scattering reveals that Trm7–Trm734 exists as a hetero-dimer in solution. Trm7 possesses a Rossmann-fold catalytic domain, while Trm734 consists of three WD40 β-propeller domains (termed BPA, BPB and BPC). BPA and BPC form a unique V-shaped cleft, which docks to Trm7. The C-terminal region of Trm7 is required for binding to Trm734. The D-arm of substrate tRNA is required for methylation by Trm7–Trm734. If the D-arm in tRNAPhe is docked onto the positively charged area of BPB in Trm734, the anticodon-loop is located near the catalytic pocket of Trm7. This model suggests that Trm734 is required for correct positioning of tRNA for methylation. Additionally, a point-mutation in Trm7, which is observed in FTSJ1 (human Trm7 ortholog) of nosyndromic X-linked intellectual disability patients, decreases the methylation activity.

Anion-π-Directed Self-Assembly between Di- and Trisulfonates and a Rigid Molecular Cage with Three Electron-Deficient V-Clefts.

Anion-π-directed self-assembly between a series of di- and trisulfonate anions and a rigid molecular cage 1 was presented. The self-assembly study was established on a combination of X-ray crystallography, NMR, mass spectrometry (MS), and scanning electron microscopy (SEM) techniques. As revealed in the crystal structures, the cage provided two V-shaped electron-deficient clefts to accommodate sulfonate groups through anion-π interactions. Depending on their structure, the series of anions showed different intermolecular interaction details with the cage and led to the formation of diverse self-assembly motifs. For 1,2-ethanedisulfonate (EDS2-), 1,3-propanedisulfonate (PDS2-), and 1,4-butanedisulfonate (BDS2-), very similar and uniform 2D ladder-like self-assemblies were formed. For 1,6-hexanedisulfonate (HDS2-) with a longer alkyl chain, a helical chain assembly was formed, while 1,3,5-tris(4-sulfophenyl)benzene (TSPB3-) led to a 3D frame structure. In solution, NMR titrations suggested that the cage can complex these anions, with association constants falling in range of 5-114 M-1. NMR spectra recorded at variable concentrations and temperatures and electrospray ionization MS further confirmed self-assembly formation. The morphologies of the diverse self-assemblies formed between the cage and sulfonates were revealed by SEM. This study, hence, provides evidence that anion-π interactions can play decisive roles in self-assembly.

Structures of endo-1,5-α-L-arabinanase mutants from Bacillus thermodenitrificans TS-3 in complex with arabino-oligosaccharides.

The thermostable endo-1,5-α-L-arabinanase from Bacillus thermodenitrificans TS-3 (ABN-TS) hydrolyzes the α-1,5-L-arabinofuranoside linkages of arabinan. In this study, the crystal structures of inactive ABN-TS mutants, D27A and D147N, were determined in complex with arabino-oligosaccharides. The crystal structures revealed that ABN-TS has at least six subsites in the deep V-shaped cleft formed across one face of the propeller structure. The structural features indicate that substrate recognition is profoundly influenced by the remote subsites as well as by the subsites surrounding the active center. The `open' structure of the substrate-binding cleft of the endo-acting ABN-TS is suitable for the random binding of several sugar units in polymeric substrates.

Characterization and functional analysis of transcription factor ZmEIL1 in maize

As key nuclear transcription factors, the ethylene-insensitive3/EIN3-like (EIN3/EIL) proteins play important roles in ethylene signal transduction pathway in various plants. In order to better understand the role of EIN3/EILs, one EIN3-like gene (designated ZmEIL1) was isolated from maize (Zea mays L.). The full-length cDNA of ZmEIL1 was 1 999 bp in length and encoded 647 amino acids. Sequence comparison of ZmEIL1 protein with other EIN3/EILs proteins revealed high conservation of five α-helices that could form a V-shaped cleft in a 3-D model, just like AtEIL3 in Arabidopsis thaliana. This protein showed transcriptional activation and activation domain located on the 507 - 647 amino acids in yeast. Furthermore, ZmEIL1 could interact with ZmERF1 in the yeast systems, which was downstream response factor in ethylene signal transduction pathway. Its mRNA could be highly induced in maize seedlings by ethephon and 1-methylcyclopropene treatments. Meanwhile, ZmEIL1 showed relatively high expression at 20 d after pollination in maize kernel. These results show that ZmEIL1 played an important role in the growth and development by participating in ethylene signalling pathway in maize.

Diagnosis of mitral valve cleft using real-time 3-dimensional echocardiography.

Mitral valve cleft (MVC) is the most common cause of congenital mitral insufficiency, and MVC may occur alone or in association with other congenital heart lesions. Direct suture and valvuloplasty are the major and effective treatments for mitral regurgitation (MR) caused by MVC. Therefore, it is important to determine the location and magnitude of the pathological damage due to MVC when selecting a surgical procedure for treatment. This study explored the application value of transthoracic real-time 3-dimensional (3D) echocardiography (RT-3DE) in the diagnosis of MVC. From October 2012 to June 2016, 19 consecutive patients with MVC diagnosed by 2-dimensional (2D) echocardiography in our hospital were selected for this study. Full-volume RT-3DE was performed on all patients. The 3D-imaging data were cropped and rotated in 3 views (horizontal, sagittal, and coronal) with 6 directions to observe the position and shape of the MVC and the spatial position between the cleft and its surrounding structures. The maximum longitudinal diameter and the maximum width of the cleft were measured. The origin of the mitral regurgitant jet and the severity of MR were evaluated, and these RT-3DE data were compared with the intraoperative findings. Of the 19 patients studied, 4 patients had isolated cleft mitral valve, and cleft mitral valves combined with other congenital heart lesions were detected in 15 patients. The clefts of 6 patients were located in the A2 segment, the clefts of 4 patients were located in the A1 segment, the clefts of 4 patients were located in the A3 segment, the clefts of 4 patients were located in the A2-A3 segment, and the cleft of 1 patient was located in the P2 segment. Regarding the shape of the cleft, 13 patients had V-shaped clefts, and the others had C- or S-shaped clefts. The severity of the MR at presentation was mild in 2 patients, moderate in 9 and severe in 8. Two of the patients with mild MR did not undergo surgery, while the remaining 17 patients did undergo surgery. Surgical treatment involved direct suture in 11 cases, reconstruction with ring annuloplasty in 3 cases and replacement in 3 cases. The diagnoses of MVC were confirmed by intraoperative findings. RT-3DE successfully captured full-volume 3D images of the 19 patients, which directly displayed the 3D structure of MVC with multiple views such as the position, shape, longitudinal diameter and width of the MVC, and the spatial position between the chordae tendineae surrounding the MVC and the aortic valve. The maximum longitudinal diameter of the valve leaflet cleft measured by RT-3DE and direct measurements during surgery were 12.02±2.12 and 13.01±2.45 mm, respectively, and the difference between these measurements was not statistically significant (P>0.05). Our results indicate that RT-3DE can provide more direct, accurate and abundant information. RT-3DE is a simple and fast imaging technique, and the detailed 3D images obtained can be used to confirm the diagnosis of MVC. RT-3DE is considered to be an important preoperative test that provides more comprehensive information for selecting a subsequent procedure for treatment.

Metal binding mediated conformational change of XPA protein:a potential cytotoxic mechanism of nickel in the nucleotide excision repair

Nucleotide excision repair (NER) is a pivotal life process for repairing DNA nucleotide mismatch caused by chemicals, metal ions, radiation, and other factors. As the initiation step of NER, the xeroderma pigmentosum complementation group A protein (XPA) recognizes damaged DNA molecules, and recruits the replication protein A (RPA), another important player in the NER process. The stability of the Zn(2+)-chelated Zn-finger domain of XPA center core portion (i.e., XPA98-210) is the foundation of its biological functionality, while the displacement of the Zn(2+) by toxic metal ions (such as Ni(2+), a known human carcinogen and allergen) may impair the effectiveness of NER and hence elevate the chance of carcinogenesis. In this study, we first calculated the force field parameters for the bonded model in the metal center of the XPA98-210 system, showing that the calculated results, including charges, bonds, angles etc., are congruent with previously reported results measured by spectrometry experiments and quantum chemistry computation. Then, comparative molecular dynamics simulations using these parameters revealed the changes in the conformation and motion mode of XPA98-210 Zn-finger after the substitution of Zn(2+) by Ni(2+). The results showed that Ni(2+) dramatically disrupted the relative positions of the four Cys residues in the Zn-finger structure, forcing them to collapse from a tetrahedron into an almost planar structure. Finally, we acquired the binding mode of XPA98-210 with its ligands RPA70N and DNA based on molecular docking and structural alignment. We found that XPA98-210's Zn-finger domain primarily binds to a V-shaped cleft in RPA70N, while the cationic band in its C-terminal subdomain participates in the recognition of damaged DNA. In addition, this article sheds light on the multi-component interaction pattern among XPA, DNA, and other NER-related proteins (i.e., RPA70N, RPA70A, RPA70B, RPA70C, RPA32, and RPA14) based on previously reported structural biology information. Thus, we derived a putative cytotoxic mechanism associated with the nickel ion, where the Ni(2+) disrupts the conformation of the XPA Zn-finger, directly weakening its interaction with RPA70N, and thus lowering the effectiveness of the NER process. In sum, this work not only provides a theoretical insight into the multi-protein interactions involved in the NER process and potential cytotoxic mechanism associated with Ni(2+) binding in XPA, but may also facilitate rational anti-cancer drug design based on the NER mechanism.

Use of the "Septal T" as a Spacer and Conformer for a Properly Contoured Nasal Tip in Rhinoplasty.

The complex issue of obtaining an aesthetically pleasing and structurally stable nasal tip brings into play a vast array of maneuvers and techniques, often performed through an open approach.1 Although these approaches are numerous and different, they all share the attainment of a stable tip cartilaginous structure, and then, if necessary, some sort of refinement or camouflage on top. An obvious situation in which such camouflage is unnecessary is the thick-skinned patient for whom sharp definition intrinsically may be welcome. As epitomized by Daniel,2,3 the ideal tip configuration will usually resemble a gently opened diamond. A similar concept is found, often with different suture terminology, in the work of other well-known surgeons.4,5 After appropriate repositioning, tensioning, or stiffening of the lateral crura as necessary, transdomal and interdomal sutures will be used to appropriately shape the domes and allow the gentle anterior domal divergence that will be stabilized by posterior dome equalization sutures. Some final camouflage may be necessary at this point. Various grafts are commonly utilized for this purpose, including segments from the cephalic trim, intercrural soft tissue, crushed cartilage, or even deep temporal fascia if harvested for other reasons.6,7 A specific drawback that will oftentimes detract somewhat from the result of an otherwise well-executed rhinoseptoplasty is a residual V-shaped infralobular cleft, extending from between the domes to the middle and medial crura. This is obviously more evident with thin skin and can be bothersome to the patient preoperatively. In such a patient, the surgeon must note the necessity of gently filling the gap between the new domes, as well as the indentation in continuity that flows below the columellar lobular angle and resides between the medial crural segments along the columella. Beginning in 2014, the senior author (E.R.) noticed …

Role of phospholipids of subunit III in the regulation of structural rearrangements in cytochrome c oxidase of Rhodobacter sphaeroides.

Subunit III of cytochrome c oxidase possesses structural domains that contain conserved phospholipid binding sites. Mutations within these domains induce a loss of phospholipid binding, coinciding with decreased electron transfer activity. Functional and structural roles for phospholipids in the enzyme from Rhodobacter sphaeroides have been investigated. Upon the removal of intrinsic lipids using phospholipase A2, electron transfer activity was decreased 30-50%. Moreover, the delipidated enzyme exhibited turnover-induced, suicide inactivation, which was reversed by the addition of exogenous lipids, most specifically by cardiolipin. Cardiolipin exhibited two sites of interaction with the delipidated enzyme, a high-affinity site (Km = 0.14 μM) and a low-affinity site (Km = 26 μM). Subunit I of the delipidated enzyme exhibited a faster digestion rate when it was treated with α-chymotrypsin compared to that of the wild-type enzyme, suggesting that lipid removal induces a conformational change to expose the digestion sites further. Upon reaction of subunit III of the enzyme with a fluorophore (AEDANS), fluorescence anisotropy showed an increased rotational rate of the fluorophore in the absence of lipids, indicating increased flexibility of subunit III within the enzyme's tertiary structure. Additionally, Förster resonance energy transfer between AEDANS and a fluorescently labeled cardiolipin revealed that cardiolipin binds in the v-shaped cleft of subunit III in the delipidated enzyme and that it moves closer to the active site in subunit I upon a change in the redox state of the enzyme. In conclusion, these results show that the phospholipids regulate events occurring during electron transfer activity by maintaining the structural integrity of the enzyme at the active site.

New species of the harvestmen Hutamaia (Laniatores: Gonyleptidae: Ampycinae) and generic diagnosis

We add three new species to the formerly monotypic Amazonian Hutamaia, Hutamaia maceta sp. nov. , Hutamaia plei sp. nov. and Hutamaia trompsonica sp. nov. and compare them with the type species, Hutamaia caramaschii Soares & Soares, 1977. Hutamaia was known only from two localities: Humaita, Amazonas, Brazil (type locality of the type species), and Madre de Dios, Peru. Herein we record species from the following additional localities, all in Brazil: Coari, Codajas, Jurua, Jutai, Manacapuru, Tefe (state of Amazonas) and Gurupa (state of Para), indicating that the genus has a widespread distribution in the Brazilian and Peruvian Amazon. Hutamaia is newly diagnosed by having yellowish granules on dorsal scutum, armature of coxa IV of males, metatarsi with yellow rings, ventral plate of penis trapezoid with V-shaped cleft, bearing two pairs of longitudinal rows of setae, and glans without dorsal or ventral processes. The genus is likely closely related to Licornus Roewer, 1932, from which it differs by the shape of the ventral plate of the penis and lack of dorsal process of glans.

Anion-Binding Properties of π-Electron Deficient Cavities in Bis(tetraoxacalix[2]arene[2]triazine): A Theoretical Study

The anion recognition by synthetic host molecules is an important theme in supramolecular chemistry. Bis(tetraoxacalix[2]arene[2]triazine) is a conformationally rigid cage molecule with three V-shaped clefts, each constituted by two electron-deficient triazine rings and two aryl C-H moieties. Its halide-binding properties are investigated in this work by quantum chemistry methods. The calculated Gibbs free energies display similar trends as the experimental observations. It has been shown that different types of noncovalent interactions including H-bond, anion-π, and lone-pair-π interactions are concurrent, leading to a cooperative effect. The respective contributions of the interactions to the overall stability are evaluated by using appropriate reference systems, with the anion-π interactions found to be as significant as the hydrogen bond interactions. In addition, in the presence of a water molecule, the stability of the ternary complexes has enhanced greatly in comparison with the binary complexes. Investigations of the solvent effect by the continuum solvent model show that the anion binding energies decrease with increasing solvent polarities. The weak halide binding energies in solution indicate that the reversible binding interactions with bis(tetraoxacalix[2]arene[2]triazine) can offer potential applications for anion transport in the membrane environment.

Structural and Functional Effects of C-Terminal Truncations in Cytochrome c Oxidase Subunit III from Rhodobacter Sphaeroides

Cytochrome c oxidase (COX) catalyzes the oxidation of ferrocytochrome c and reduction of oxygen to water while pumping protons across the inner mitochondrial or bacterial membrane. In this work, two R. sphaeroides COX subunit III (SIII) truncation mutations which mimic those observed in human mitohcondria were characterized. One truncation created was after the third helix of SIII (Δ114 SIII), while the other was after the sixth helix (Δ238 SIII). Isolated and purified Δ114 SIII and the Δ228 SIII retained at least 70% and 30%, respectively of its SIII content. MALDI-TOF showed that Δ114 SIII and I/II COX (where SIII was genetically deleted) had altered in vivo processing of subunits II and IV. Electron transfer assays showed that Δ114 SIII and Δ238 SIII were inhibited by 50% and 70%, compared to control COX. The pH dependencies of the electron transfer rate in both mutations and I/II COX were similar (pKa= 7.4), as compared to wild-type (pKa= 8.7). Both mutations underwent turnover induced inactivation; however, when Δ114 SIII was supplemented with 1 mg/ml asolectin in the assay buffer, the catalytic lifetime of increased two fold when compared to I/II COX. Δ114 SIII and Δ238 SIII exhibited proton-pumping stoichiometries of 0.40 and 0.32, as compared to 0.76 wild-type COX and 0.38 for I-II COX. These results indicate that the five C-terminal helices in SIII play a critical role in the processing of subunits II and IV and in the assembly of COX. Also, structural lipids within the v-shaped cleft of SIII are necessary for providing protection against turnover induced inactivation, and that perturbation in the structure of SIII results in a lower efficiency of vectorial proton pumping by modifying the conformation of subunit I.

Structural and Biochemical Insights into MLL1 Core Complex Assembly

Histone H3 Lys-4 methylation is predominantly catalyzed by a family of methyltransferases whose enzymatic activity depends on their interaction with a three-subunit complex composed of WDR5, RbBP5, and Ash2L. Here, we report that a segment of 50 residues of RbBP5 bridges the Ash2L C-terminal domain to WDR5. The crystal structure of WDR5 in ternary complex with RbBP5 and MLL1 reveals that both proteins binds peptide-binding clefts located on opposite sides of WDR5's β-propeller domain. RbBP5 engages in several hydrogen bonds and van der Waals contacts within a V-shaped cleft formed by the junction of two blades on WDR5. Mutational analyses of both the WDR5 V-shaped cleft and RbBP5 residues reveal that the interactions between RbBP5 and WDR5 are important for the stimulation of MLL1 methyltransferase activity. Overall, this study provides the structural basis underlying the formation of the WDR5-RbBP5 subcomplex and further highlight the crucial role of WDR5 in scaffolding the MLL1 core complex.

Synthesis, Structure and Molecular Recognition of Functionalised Tetraoxacalix[2]arene[2]triazines

Functionalised dialkoxy-substituted tetraoxacalix[2]arene[2]triazine macrocycles 6 have been readily synthesised by the fragment coupling approach using methyl 3,5-dihydroxy-4-alkoxybenzoates and cyanuric chloride as the starting materials under very mild conditions. AlCl(3)-mediated deallylation and debenzylation reactions afforded the lower-rim dihydroxy-substituted tetraoxacalix[2]arene[2]triazine derivatives 11 and 13 in good yields. Although dialkoxy-substituted tetraoxacalix[2]arene[2]triazine macrocycles are fluxional in solution on the NMR spectroscopy timescale, they adopt a symmetric or slightly distorted 1,3-alternate conformation with the bridging oxygen atoms conjugated with the triazine rings. The dihydroxylated tetraoxacalix[2]arene[2]triazine 13 b, which gives a mixture of monomer and dimer in solution according to a diffusion NMR spectroscopy study, adopts a 1,3-alternate conformation and forms a cyclic tetrameric assembly in the solid state due to the formation of intermolecular hydrogen-bonding networks. This dihydroxylated macrocyclic host molecule, a hydrogen-bond donor macrocycle with a V-shaped cleft, interacts with 2,2'-bipyridine, 4,4'-bipyridine and 1,10-phenanthroline guests. Although in solution they form the corresponding 1:1 complexes with binding constants ranging from 37.7 to 213 M(-1), 2:2 host-guest complexes were observed in the crystalline state. Hydrogen-bonding interactions, along with other non-covalent interactions, such as lone-pair-electron-pi and C-H...pi interactions, were found to be the driving force for the formation of host-guest complexes.

Anomalous Inclusion Behavior Shown by a Thia-Bridged Diquinoline Derivative

The sulfur-bridged compound 6,7,14,15-tetrahydro-6,14-thiacycloocta[1,2-b:5,6-b′]diquinoline (11) yields a solvent-free crystal form but also produces lattice inclusion compounds containing chloroform, water, and methanol. This latter behavior is in marked contrast to the noninclusion characteristics shown by its corresponding oxygen- and methano-bridged analogues. X-ray structures of the three different crystal types formed by 11 reveal that all contain a two-molecule repeat unit in which the S atom of the first is located within the V-shaped cleft of the second. This assembly is reminiscent of a ball and socket joint, and the adoption of this motif is the root cause of the unexpected solid-state inclusion properties shown by 11.

Microform or Incomplete Median Cleft Lip: Strategy and Management

Sir: Median cleft of the upper lip is a congenital midline vertical cleft because of the absence of the prolabium. Long-term data and a treatment algorithm for the minor form of median cleft deformity and its associated problem (e.g., frenula anomalies and upper incisor diastema) are lacking. This retrospective review includes five patients between 1982 to 1994, two male and three female patients. The follow-up ranged from 10 to 20 years. The patients exhibited microform median cleft of the upper lip and survived like other normal infants. The straight-line lip repair was performed at 3 months of age (Fig. 1) and followed by orthodontic treatment. The skin lining was excised and the mucosa, orbicularis oris muscle, and skin were repaired without Z-plasty or other lengthening techniques. Alveolar bone grafting was also performed at the age of 5 years, before eruption of the permanent maxillary incisors.1 The results were evaluated by using the classification published by Abyholm et al.2 and evaluated by occlusal radiographs 1 week, 6 months, and 1 year after surgery.Fig. 1.: One midline notch on the upper lip and extending halfway up the philtrum. A median dysgenesis remnant was localized in the central part of the philtrum.An aesthetic and symmetrical philtrum column and upper lip were achieved. The length of the philtrum column was adequate (Fig. 2). All patients achieved type I results of alveolar bone grafting, and the dental radiographs showed new bone reaching alveolar ridges. Long-term dental occlusion proved stable results of diastema correction.Fig. 2.: Good symmetry of vermilion and Cupid's bow, minimized scar formation, and adequate length of the upper lip were achieved.Pathologic findings of the remnant in the first case demonstrated cutaneous tissue with a partial cartilaginous component that was different from the pure cutaneous component in other articles. In this series, the straight-line technique was chosen instead of the forked flap procedure described by Millard to correct the upper lip notch at 3 months of age.3 The midline ridge was excised, narrowed, and lengthened by advancement of the forked flap in his series. The straight-line mark along the bilateral philtrum column margin was designed. Simple excision helps narrow the column, maintain the concavity, and avoid altering the Cupid's bow and tubercle. The adequate length and nondisfigured philtrum and symmetric upper lip indicate that it was not necessary to use specific techniques to camouflage the upper lip scar. A median cleft associated with alveolus cleft and diastema has been described.4 Diastema caused by midline bony clefts tends to relapse earlier and was resistant to conventional treatment.5 The relationship between notching on the upper lip and relapse of maxillary diastema was also reported. A V-shaped bony cleft between two central incisors typically occurs in these patients. The bony cleft interrupts the formation of transeptal fibers and fails to proliferate across the midline cleft. In brief, restoration of bony support should precede the orthodontic correction in incisor diastema. Early secondary bone grafting was performed between 4 and 7 years of age. We recommend bone grafting at the age of 5 years, before permanent incisor eruption. Successful bone grafting provides better support when new teeth erupt and helps maintain subsequent orthodontic results. In our series, diastema larger than 4 mm may be aesthetically and functionally restored by early bone grafting. Erh-Kang Chou, M.D. Department of Plastic Surgery China Medical University Hospital Taichung, and School of Medicine China Medical University Taichung, Taiwan Ellen Wen-Ching Ko, D.D.S., M.S. Department of Dentistry Philip Kuo-Ting Chen, M.D. Department of Plastic Surgery Chang Gung Memorial Hospital Chang Gung University College of Medicine Taoyuan, Taiwan Jack Chung-Kai Yu, M.D., D.M.D. Section of Plastic and Reconstructive Surgery Medical College of Georgia Augusta, Ga. Sophia Chia-Ning Chang, M.D., Ph.D. Department of Plastic Surgery China Medical University Hospital Taichung, and School of Medicine China Medical University Taichung, Taiwan