Primary Motif Research Articles

Facile preparation of optically pure diamines and their applications in asymmetric aldol reactions

A family of optically pure diamines with tertiary–primary amine motif has been synthesized from optically pure binaphthol and amino acids. The catalysts are highly tunable in structure and has demonstrated high efficiency in direct aldol reactions. Thus, a variety of aldehydes or methyl 2-oxoacetates reacted with acetone in the presence of 10 mol % of catalyst and 20 mol % TFA, furnishing the desired alcohols in up to 99% yield with excellent enantioselectivities (up to 96% ee).

Bioinformatic analysis of the CLE signaling peptide family.

BackgroundPlants encode a large number of leucine-rich repeat receptor-like kinases. Legumes encode several LRR-RLK linked to the process of root nodule formation, the ligands of which are unknown. To identify ligands for these receptors, we used a combination of profile hidden Markov models and position-specific iterative BLAST, allowing us to detect new members of the CLV3/ESR (CLE) protein family from publicly available sequence databases.ResultsWe identified 114 new members of the CLE protein family from various plant species, as well as five protein sequences containing multiple CLE domains. We were able to cluster the CLE domain proteins into 13 distinct groups based on their pairwise similarities in the primary CLE motif. In addition, we identified secondary motifs that coincide with our sequence clusters. The groupings based on the CLE motifs correlate with known biological functions of CLE signaling peptides and are analogous to groupings based on phylogenetic analysis and ectopic overexpression studies. We tested the biological function of two of the predicted CLE signaling peptides in the legume Medicago truncatula. These peptides inhibit the activity of the root apical and lateral root meristems in a manner consistent with our functional predictions based on other CLE signaling peptides clustering in the same groups.ConclusionOur analysis provides an identification and classification of a large number of novel potential CLE signaling peptides. The additional motifs we found could lead to future discovery of recognition sites for processing peptidases as well as predictions for receptor binding specificity.

Hydrogen bonding patterns in a series of 1-arylcycloalkanecarboxamides

Single-crystal structures of five 1-arylcycloalkanecarboxamides, viz.1-phenylcyclopentanecarboxamide (1), 1-phenylcyclohexanecarboxamide (2), 1-(2-fluorophenyl)cyclohexanecarboxamide (3), 1-(2-chlorophenyl)cyclohexanecarboxamide (4) and 1-(2-bromophenyl)-cyclohexanecarboxamide (5), are reported. The primary hydrogen-bonded motif consists of centrosymmetric or non-centrosymmetric R22(8) dimers between the carboxamide functional groups. In compound 1, the dimers are further linked by hydrogen bonds to form infinite two-dimensional sheets, while in 4 and 5 additional hydrogen bonding with molecules not involved in dimer formation links the dimers into infinite chains. The cycloalkane rings in the five compounds adopt noticeably different conformations. As a consequence of these various effects, none of the five compounds is isostructural.

Balancing Hydrogen-Bond Donors and Acceptors in a Family of Bifunctional Aromatic N-Heterocycles

A series of bifunctional pyridine-aminopyrimidine/aminopyridine supramolecular reagents (SRs) have been synthesized through palladium-catalyzed cross-coupling reactions and characterized by single-crystal X-ray crystallography. 3-(2-Amino-4-methylpyrimidin-6-yl)pyridine 1, 4-(2-amino-4-methylpyrimidin-6-yl)pyridine 2, and 4-methoxy-3-(2-amino-4-methylpyrimidin-6-yl)pyridine 3 were synthesized via Suzuki-Miyaura cross-coupling conditions in good yields, whereas 1-(2-amino-4-methylpyrimidin-6-yl)-2-(3-methoxypyridin-5-yl)ethyne 4, 1-(2-aminopyrid-5-yl)-2-(pyrid-3-yl)ethyne 5, and 1-(6-amino-3-pyridyl)-2-(4-{benzimidazol-1-yl}phenyl)ethyne 6 were synthesized through conventional Sonogashira cross-coupling conditions. The primary hydrogen-bonding motif in solid-state structures 1–5 is a self-complementary amino-pyrimidine N–H···N/N···H–N synthon, whereas adjacent molecules in the structure of 6 are connected via aminopyridine-benzimidazole N–H···N hydrogen bonds. Secondary anti-amino proton/pyridyl N–H···N hy...

Distance semantics for database repair

In many scenarios, a database instance violates a given set of integrity constraints. In such cases, it is often required to repair the database, that is, to restore its consistency. A primary motif behind the repairing approaches is the principle of minimal change, which is the aspiration to keep the recovered data as faithful as possible to the original (inconsistent) database. In this paper, we represent this qualitative principle quantitatively, in terms of distance functions and some underlying metrics, and so introduce a general framework for repairing inconsistent databases by distance-based considerations. The uniform way of representing repairs and their semantics clarifies the essence behind several approaches to consistency restoration in database systems, helps to compare the underlying formalisms, and relates them to existing methods of defining belief revision operators, merging data sets, and integrating information systems.

Crystal packing of two 5-substituted 2-methyl-4-nitro-1H-imidazoles

Infinite chains connected by N-H...N hydrogen bonding form the primary packing motif in two closely related 4-nitroimidazole derivatives, viz. 5-bromo-2-methyl-4-nitro-1H-imidazole, C(4)H(4)BrN(3)O(2), (I), and 2-methyl-4-nitro-1H-imidazole-5-carbonitrile, C(5)H(4)N(4)O(2), (II). These chains are almost identical, even though in (II) there are two symmetry-independent molecules in the asymmetric unit. The differences appear in the interactions between the chains; in (I), there are strong C-Br...O halogen bonds, which connect the chains into a two-dimensional grid, while in (II), the cyano group does not participate in specific interactions and the chains are only loosely connected into a three-dimensional structure.

Molecular packing in (5-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)acetamide

In the title compound, C7H9N3O3, the primary packing motif, viz. an infinite tape, is formed via intermolecular hydrogen bonds of different strengths. In the formation of the tapes, only inversion centres are used; the other symmetry elements of P2(1)/c connect the tapes into a three-dimensional structure through only weak hydrogen bonds.

Differential Expression of CD45 Isoforms Is Controlled by the Combined Activity of Basal and Inducible Splicing-regulatory Elements in Each of the Variable Exons

The human CD45 gene encodes five isoforms of a transmembrane tyrosine phosphatase that differ in their extracellular domains as a result of alternative splicing of exons 4-6. Expression of the CD45 isoforms is tightly regulated in peripheral T cells such that resting cells predominantly express the larger CD45 isoforms, encoded by mRNAs containing two or three variable exons. In contrast, activated T cells express CD45 isoforms encoded by mRNAs lacking most or all of the variable exons. We have previously identified the sequences within CD45 variable exon 4 that control its level of inclusion into spliced mRNAs. Here we map the splicingregulatory sequences within CD45 variable exons 5 and 6. We show that, like exon 4, exons 5 and 6 each contain an exonic splicing silencer (ESS) and an exonic splicing enhancer (ESE), which together determine the level of exon inclusion in naïve cells. We further demonstrate that the primary activation-responsive silencing motif in exons 5 and 6 is homologous to that in exon 4 and, as in exon 4, binds specifically to the protein heterogeneous nuclear ribonucleoprotein L. Together these studies reveal common themes in the regulation of the CD45 variable exons and provide a mechanistic explanation for the observed physiological expression of CD45 isoforms.

Cell surface counter receptors are essential components of the unconventional export machinery of galectin-1

Galectin-1 is a component of the extracellular matrix as well as a ligand of cell surface counter receptors such as β-galactoside–containing glycolipids, however, the molecular mechanism of galectin-1 secretion has remained elusive. Based on a nonbiased screen for galectin-1 export mutants we have identified 26 single amino acid changes that cause a defect of both export and binding to counter receptors. When wild-type galectin-1 was analyzed in CHO clone 13 cells, a mutant cell line incapable of expressing functional galectin-1 counter receptors, secretion was blocked. Intriguingly, we also find that a distant relative of galectin-1, the fungal lectin CGL-2, is a substrate for nonclassical export from Chinese hamster ovary (CHO) cells. Alike mammalian galectin-1, a CGL-2 mutant defective in β-galactoside binding, does not get exported from CHO cells. We conclude that the β-galactoside binding site represents the primary targeting motif of galectins defining a galectin export machinery that makes use of β-galactoside–containing surface molecules as export receptors for intracellular galectin-1.

The modular xylanase Xyn10A from Rhodothermus marinus is cell-attached, and its C-terminal domain has several putative homologues among cell-attached proteins within the phylum Bacteroidetes

Until recently, the function of the fifth domain of the thermostable modular xylanase Xyn10A from Rhodothermus marinus was unresolved. A putative homologue to this domain was however identified in a mannanase (Man26A) from the same microorganism which raised questions regarding a common function. An extensive search of all accessible data-bases as well as the partially sequenced genomes of R. marinus and Cytophaga hutchinsonii showed that homologues of this domain were encoded by multiple genes in microorganisms in the phylum Bacteroidetes. Moreover, the domain occurred invariably at the C-termini of proteins that were predominantly extra-cellular/cell attached. A primary structure motif of three conserved regions including structurally important glycines and a proline was also identified suggesting a conserved 3D fold. This bioinformatic evidence suggested a possible role of this domain in mediating cell attachment. To confirm this theory, R. marinus was grown, and activity assays showed that the major part of the xylanase activity was connected to whole cells. Moreover, immunocytochemical detection using a Xyn10A-specific antibody proved presence of Xyn10A on the R. marinus cell surface. In the light of this, a revision of experimental data present on both Xyn10A and Man26A was performed, and the results all indicate a cell-anchoring role of the domain, suggesting that this domain represents a novel type of module that mediates cell attachment in proteins originating from members of the phylum Bacteroidetes.

Molecular interaction of retinoic acid receptors with coregulators PCAF and RIP140

p300/CBP-associating factor (PCAF) is a ligand-dependent coactivator, whereas receptor-interacting protein 140 (RIP140) is a ligand-dependent negative coregulator for retinoic acid (RA) receptor (RAR) and retinoid X receptor (RXR). To compare these molecular interactions and to determine the effect of RXR ligands, we focus on PCAF/RAR/RXR complex formation in this study for a comparison to RIP140/RAR/RXR complex formation. The LBD of RXR is identified as its primary PCAF-interacting motif. BIAcore studies determine the K d of RAR/RXR association with PCAF as 9.35 nM in the presence of RXR ligand AGN194204, and 47.2 nM in the absence of ligand. Cross-linking study demonstrates tri-molecular complex consisting of one RAR/RXR pair and one PCAF. In competition experiments, RIP140 strongly competes with PCAF for interaction with RAR/RXR both in vitro and in vivo. Chromatin immunoprecipitation demonstrates recruitment of RIP140 and PCAF to the endogenous RA-regulated gene, the RARβ2 promoter. This study presents kinetic evidence for competition of RIP140 with PCAF for ligand-dependent interactions with RAR/RXR, and provides kinetic explanation for the suppressive activity of RIP140 in RA-activated gene expression.

Chiral Bis(amino alcohol)oxalamide Gelators—Gelation Properties and Supramolecular Organization: Racemate versus Pure Enantiomer Gelation

Four new chiral bis(amino alcohol)oxalamides (1-4: amino alcohol=leucinol, valinol, phenylglycinol, and phenylalaninol, respectively) have been prepared as low-molecular-weight organic gelators. Their gelation properties towards various organic solvents and mixtures were determined and these were then compared to related bis(amino acid) oxalamide gelators. Spectroscopic (FTIR, (1)H NMR) and X-ray diffraction studies revealed that the primary organization motif of (S,S)-1 and racemate 1 (rac-1) in lipophilic solvents involved the formation of inverse bilayers. The X-ray crystal structure of (S,S)-1 also shows this type of bilayer organization. The crystal structure of rac-2 reveals meso bilayers of hydrogen-bonded aggregates. Within the bilayers formed, the gelator molecules are connected by cooperative hydrogen bonding between oxalamide units and OH groups, while the interbilayer interactions are realized through lipophilic interactions between the iBu groups of leucinol. Oxalamide meso-1 lacks any gelation ability and crystallizes in monolayers. In dichloromethane rac-1 forms an unstable gel; this is prone to crystallization as a result of the formation of symmetrical meso bilayers. In contrast, in aromatic solvents rac-1 forms stable gels; this indicates that enantiomeric bilayers are formed. Oxalamide rac-1 is capable of gelling a volume of toluene three times larger than (S,S)-1. A tranmission electron microscopy investigation of rac-1 and (S,S)-1 toluene gels reveals the presence of thinner fibers in the former gel, and, hence, a more compact network that is capable of immobilizing a larger volume of the solvent. The self-assembly of these types of gelator molecules into bilayers and subsequent formation of fibrous aggregates can be explained by considering the strength and direction of aggregate forces (supramolecular vectors) in three-dimensional space.

Cooperative dimerization of a heterocyclic diamidine determines sequence-specific DNA recognition.

In the course of a program aimed at discovering novel DNA-targeted antiparasitic drugs, the phenylfuran-benzimidazole unfused aromatic dication DB293 was identified as the first diamidine capable of forming stacked dimers in the DNA minor groove of GC-containing sequences. Its preferred binding sequence encompasses the tetranucleotide 5'-ATGA.5'-TCAT to which DB293 binds tightly with a strong positive cooperativity. Here we have investigated the influence of the DNA sequence on drug binding using two complementary technical approaches: surface plasmon resonance and DNase I footprinting. The central dinucleotide of the primary ATGA motif was systematically varied to represent all of the eight possible combinations (AXGA and ATYA, where X or Y = A, T, G, or C). Binding affinities for each site were precisely measured by SPR, and the extent of cooperative drug binding was also determined. The sequence recognition process was found to be extremely dependent on the nature of the central dinucleotide pair. Modification of the central TG step decreases binding affinity by a factor varying from 2 to over 500 depending on the base substitution. However, the diminished binding affinity does not affect the unique binding mode. In nearly all cases, the SPR titrations revealed a positive cooperativity in complex formation which reflects the ease of the dication to form stacked dimeric motifs in the DNA minor groove. DNase I footprinting served to identify additional binding sites for DB293 in the context of long DNA sequences offering a large variety of randomly distributed or specifically designed sites. The ATGA motif provided the best receptor for the drug, but lower affinity sequences were also identified. The design of two DNA fragments composed of various targeted tetranucleotide binding sites separated by an "insulator" (nonbinding) sequence allowed us to delineate further the influence of DNA sequence on drug binding and to identify a novel high-affinity site: 5'-ACAA.5'-TTGT. Collectively, the SPR and footprinting results show that the consensus sequence 5'-(A/T)-TG-(A/T) represents the optimal site for cooperative dimerization of the heterocyclic diamidine DB293.

Retrieval-independent localization of lysyl hydroxylase in the endoplasmic reticulum via a peptide fold in its iron-binding domain.

Lysyl hydroxylase (LH) is a peripheral membrane protein in the lumen of the endoplasmic reticulum (ER) that catalyses hydroxylation of lysine residues in collagenous sequences. Previously, we have mapped its primary ER localization motif within a 40-amino acid segment at its C-terminus. Here, we have characterized this localization mechanism in more detail, and our results indicate that this segment confers ER residency in a KDEL-receptor-independent manner, and without any apparent recycling of the enzyme between the Golgi apparatus and the ER. In addition, we show that a rather long peptide region, rather than a specific peptide sequence per se, is required for efficient retention of a reporter protein in the ER. Accordingly, the minimal retention motif was found to require the last 32 C-terminal amino acids, and sequential substitution of all five charged residues within this critical segment interfered only marginally with the retention or association of the enzyme with the ER membranes. Moreover, our fold-recognition and structure-prediction analyses suggested that this critical peptide segment forms an extended loop within LH's iron-binding domain, and that this loop is exposed and readily accessible for binding. Collectively, our results define a novel retrieval-independent retention mechanism in the ER.

Plateins: a novel family of signal peptide-containing articulins in euplotid ciliates.

In euplotid ciliates, the cortex is reinforced by alveolar plates--proteinaceous scales located within the membranous alveolar sacs, forming a monolayer just below the plasma membrane. This system appears to play a cytoskeletal role analogous to that provided by the fibrous epiplasm found beneath the cortical alveoli in other ciliates. In Euplotes aediculatus, the major alveolar plate proteins (termed alpha-, beta-, and gamma-plateins) have been identified. Using anti-platein antibodies, an expression library of Euplotes genes was screened, and a platein gene identified, cloned, and completely sequenced. Comparison of its derived amino acid sequence with microsequences obtained directly from purified plateins identified this gene as encoding one of the closely related beta- or gamma-plateins. The derived protein, of 644 amino acids (74.9 kDa), is very acidic (pI = 4.88). Microsequences from authentic alpha-platein were then used to design oligonucleotide primers, which yielded, via a PCR-based approach, the sequences of two alpha-platein genes from E. aediculatus. Even more acidic proteins, the derived alpha1- and alpha2-plateins contain 536 and 501 residues, respectively. Analyses of their amino acid sequences revealed the plateins to be members of the articulin superfamily of cytoskeletal proteins, first described in Euglena and now identified in the ciliate Pseudomicrothorax and in Plasmodium. The hallmark articulin repetitive motifs (based on degenerate valine- and proline-rich 12-mers) are present in all three plateins. In beta/gamma-platein this primary motif domain (27 repeats) is central in the molecule, whereas the primary repeats in the alpha-plateins lie near their C-termini. A cluster of proline-rich pentameric secondary repeats is found in the C-terminus of beta/gamma-platein, but near the N-terminus of alpha-plateins. All three plateins contain canonical N-terminal signal sequences, unique among known cytoskeletal proteins. The presence of start-transfer sequences correlates well with the final intra-alveolar location of these proteins. This feature, and significant differences from known articulins in amino acid usage and arrangement within the repeat domains, lead us to propose that the plateins comprise a new family of articulin-related proteins. Efforts to follow microscopically the assembly of plateins into new alveolar plates during pre-fission morphogenesis are underway.

The Gwich'in Traditional Caribou Skin Clothing Project: Repatriating Traditional Knowledge and Skills

... The Gwich'in are the most northerly of the Athapaskan peoples occupying parts of the Yukon River drainage in Alaska and the Yukon Territory, and the northern Mackenzie Basin of the Northwest Territories. The project described here was sponsored by the Gwich'in who reside in the Northwest Territories. Traditionally their lands extended from the interior of the Yukon into the Mackenzie Basin and included the watersheds of the Peel, Mackenzie, and Arctic Red Rivers. Today, most NWT Gwich'in live in the four communities of Aklavik, Fort McPherson, Inuvik, and Tsiigehtchic (formerly called Arctic Red River). These communities all fall within the Gwich'in Settlement Area that was established by the Gwich'in Comprehensive Land Claim Agreement signed in 1992 with the Government of Canada. People in the Gwich'in Settlement Area are greatly interested in materials that were collected in earlier times and are now housed throughout the world in museums, archives, and private collections. These items represent a bygone era and have great historical, cultural, and sometimes spiritual meaning. Of particular interest is traditional Gwich'in summer clothing made of white caribou hides, sewn with sinew, and decorated with porcupine quills, trade beads, silverberry seeds, finges, and ochre. Distinctively styled and striking to look at, these garments are a testament to Gwich'in women's great skill and artistic expression. ... It has been well over 100 years since Gwich'in traditional caribou skin clothing was made, and there are no examples of this clothing in either the Gwich'in communities or the Northwest Territories today. It has been over 50 years since porcupine quillwork was used as the primary decorative motif on Gwich'in jackets, slippers, and gloves. For the past two years, the Gwich'in Social and Cultural Institute (GSCI) has worked in partnership with the Prince of Wales Northern Heritage Centre (PWNHC) to create five replicas of a multipiece 19th-century Gwich'in traditional summer outfit that is housed at the Canadian Museum of Civilization (CMC). The project has given us an opportunity to document, understand, and appreciate how this clothing was manufactured and the extraordinary amount of time, knowledge, and skill that Gwich'in women needed to clothe their families and protect them from the elements. It has also helped to repatriate skills and knowledge no longer practiced in the Gwich'in Settlement Area.

Monoclonal antibodies that bind to domain III of dengue virus E glycoprotein are the most efficient blockers of virus adsorption to Vero cells.

The specific mechanisms by which antibodies neutralize flavivirus infectivity are not completely understood. To study these mechanisms in more detail, we analyzed the ability of a well-defined set of anti-dengue (DEN) virus E-glycoprotein-specific monoclonal antibodies (MAbs) to block virus adsorption to Vero cells. In contrast to previous studies, the binding sites of these MAbs were localized to one of three structural domains (I, II, and III) in the E glycoprotein. The results indicate that most MAbs that neutralize virus infectivity do so, at least in part, by the blocking of virus adsorption. However, MAbs specific for domain III were the strongest blockers of virus adsorption. These results extend our understanding of the structure-function relationships in the E glycoprotein of DEN virus and provide the first direct evidence that domain III encodes the primary flavivirus receptor-binding motif.

Lesion-targeted injectable vectors for vascular restenosis.

Pathologic lesions caused by catheter-based revascularization procedures for occlusive artery disease include disruption of the endothelium, exposure of extracellular matrix (ECM) proteins, and proliferation of vascular smooth muscle cells, which lead to neointima formation and restenosis. We have developed matrix-collagen-targeted retroviral vectors that are able to accumulate at sites of vascular injury (Hall et al., Hum. Gene Ther. 1997;8:2183-2192; Hall et al., Hum. Gene Ther. 2000;11:983-993). The primary tissue-targeting motif, adapted from the physiological surveillance sequence found in von Willebrand factor, served to localize and concentrate the vector within vascular lesions. In the present study, we evaluated the efficiency of this vector-targeting system in rats with nonligated balloon-injured carotid arteries. Both intraarterial (by retrograde femoral artery catheterization) and intravenous (via femoral vein) injection of a matrix-targeted vector enhanced transduction of neointimal cells ( approximately 20%) at severely denuded areas when compared with the nontargeted vector (<1%). Further, intraarterial instillation of a matrix-targeted, but not a nontargeted, vector bearing an antisense cyclin G1 construct inhibited neointima lesion formation in the injured carotid arteries. Taken together, these data indicate that strategic targeting of retroviral vectors to vascular lesions would have therapeutic potential in the management of vascular restenosis and many other disorders of uncontrolled proliferation where endothelial disruption, ECM remodeling, and collagen deposition form the nexus for preferential vector localization and concentration in vivo.

The crisis of public health: implications for social workers.

During the past two decades, observers have noted that the U.S. system is in a state of disarray (Institute of Medicine [IOM], 1988). A 1988 report by the IOM described as a system in shattered vision. The IOM noted that society had contributed to the problem by its failure to reach consensus on the mission of heath and the role government should play in meeting public objectives (IOM, 1988, pp. 6-7). Recent studies also warn that our system is in a state of crisis. According to Garrett (2000), although [o]nce the envy of the world, America's infrastructure is now in a state of shambles (p. 280). The authors of Health and Health Care 2010, a report prepared by the Institute for the Future (2000), predict that during the next decade, will be insufficiently funded and to address ... underlying problems...largely incremental (p. 9). column examines the crisis in and considers prospects for the future, briefly reviewing the development of in the United States and examining the curative model of health, which grew out of the separation of from clinical medicine. Finally, the column addresses the rise and limits of what many call the new and concludes with thoughts about how social workers might participate in efforts to create a new health. THE RISE AND FALL OF PUBLIC HEALTH The period between 1900 and 1930 was a age for health (Starr, 1982, p. 197). Although New York City had enacted legislation as early as 1796, and some states and created boards of during the 1840s and 1850s, opposition from business and other groups stymied these efforts. This theme--of tension between business and sectors--would repeat itself so frequently in coming decades as to constitute a primary motif of the nation's struggle for population health (Garrett, 2000, pp. 282-283). The rise of urbanization and industrialization created problems that became impossible to ignore (Haines, 1991). Although members of the upper class could escape the overcrowded cities, by moving to rural areas, members of the emerging urban middle class did not enjoy this luxury (Baltzell, 1964). They paid taxes, supported cleanliness and education, recognized and abhorred corruption, and, as home owners, had an investment in their cities (Garrett, 2000, p. 284). The middle class took the lead in advocating a wide range of reforms, including the enactment of and safety regulations (Garrett). During the 1890s many instituted new works sanitation projects (such as piped water, sewer systems, filtration and chlorination of water) and administration (Haines, p. 105). By the turn of the century, it had become increasingly clear that many diseases were communicable in nature. With the development of vaccines against rabies and diphtheria, many communities, particularly in the east, required their citizens to become immunized (Garrett, 2000). In New York City, Hermann Biggs, a leading figure, asserted that authorities could resort to any measure that was 'designed for the good' and 'beneficent' in its 'effects' (cited in Garrett, p. 297). Authorities routinely deployed police officers and zealous nurses or physicians to the homes of those suspected of carrying disease....In some cases, police officers pinned the arm of those who refused while a city nurse jabbed it with a vaccination needle (Garrett, p. 299). These efforts seemed to pay off. Between 1900 and 1915, death rates (among children) from measles, whooping cough, scarlet fever, and diphtheria fell (Garrett). The golden age of did not last long, however. In 1920 a prominent theorist defined as the science and art of preventing disease, prolonging life, and promoting and efficiency through organized community effort (cited in Starr, 1982, p. …

The crystal structure of Cys-tRNACys-EF-Tu-GDPNP reveals general and specific features in the ternary complex and in tRNA.

. The translation elongation factor EF-Tu in its GTP-bound state forms a ternary complex with any aminoacylated tRNA (aa-tRNA), except initiator tRNA and selenocysteinyl-tRNA. This complex delivers aa-tRNA to the ribosomal A site during the elongation cycle of translation. The crystal structure of the yeast Phe-tRNAPhe ternary complex with Thermus aquaticus EF-Tu-GDPNP (Phe-TC) has previously been determined as one representative of this general yet highly discriminating complex formation. The ternary complex of Escherichia coli Cys-tRNACys and T. aquaticus EF-Tu-GDPNP (Cys-TC) has been solved and refined at 2.6 degrees resolution. Conserved and variable features of the aa-tRNA recognition and binding by EF-Tu-GTP have been revealed by comparison with the Phe-TC structure. New tertiary interactions are observed in the tRNACys structure. A 'kissing complex' is observed in the very close crystal packing arrangement. The recognition of Cys-tRNACys by EF-Tu-GDPNP is restricted to the aa-tRNA motif previously identified in Phe-TC and consists of the aminoacylated 3' end, the phosphorylated 5' end and one side of the acceptor stem and T stem. The aminoacyl bond is recognized somewhat differently, yet by the same primary motif in EF-Tu, which suggests that EF-Tu adapts to subtle variations in this moiety among all aa-tRNAs. New tertiary interactions revealed by the Cys-tRNACys structure, such as a protonated C16:C59 pyrimidine pair, a G15:G48 'Levitt pair' and an s4U8:A14:A46 base triple add to the generic understanding of tRNA structure from sequence. The structure of the 'kissing complex' shows a quasicontinuous helix with a distinct shape determined by the number of base pairs.