Stable Dimer Research Articles

Accelerated Design of Dual-Metal-Site Catalysts via Machine-Learning Prediction.

Dual-metal site catalysts (DMSCs) supported on nitrogen-doped graphene have shown great potential in heterogeneous catalysis due to their unique properties and enhanced efficiency. However, the precise control and stabilization of metal dimers, particularly in oxygen activation reactions, present significant challenges in practical applications. In this study, we integrate high-throughput density functional theory calculations with machine learning techniques to predict and optimize the catalytic properties of DMSCs. Transfer learning is employed to enhance the model's generalization capability, successfully predicting catalytic performance across new metal combinations. Additionally, the application of the SISSO method enables the derivation of interpretable symbolic regression models, revealing critical correlations between electronic structure features and catalytic efficiency. This approach not only advances the understanding of dual-metal site catalysis but also provides a novel framework for the systematic design and optimization of highly efficient catalysts, with broad applicability in catalytic science.

Pancake Bonding in the Stabilization of Cationic Acene Dimers

Pancake Bonding in the Stabilization of Cationic Acene Dimers

Functional and structural characterization of mouse Factor H-related B protein unveils a novel dimerization domain shared by FHR-B and FH

Factor H-related proteins (FHRs) are found in mice, but their equivalence to human FHRs remains uncertain. This study identifies three FHRs in mouse plasma (FHR-B, FHR-C, and FHR-E) and focuses on characterizing FHR-B. Using purified plasma proteins and recombinant mutants, FHR-B was found to form dimers and bind strongly to C3, C3b, iC3b, and C3dg. It also competes with mouse Factor H (mFH) for binding to C3b-coated surfaces and disrupts mFH regulation in hemolysis assays with sheep and guinea pig erythrocytes. These functions are localized to the C-terminal region and are dependent on FHR-B dimerization. Dimerization occurs through the N-terminal region (SCR1-3), which differs from mFH SCR5-7 by only four amino acids and also shares significant homology with human FHR-3 and human FH SCR5-7. In contrast to FHR-1, AUC experiments indicate that FHR-B dimerization is pH-sensitive, reversible and that the monomers in the dimer present the same head to tail orientation. Mutant analyses revealed that mFH SCR5-7 also forms dimers, but less efficiently than FHR-B. Notably, substituting FHR-B Tyr162 (a key residue homologous to the disease-associated Tyr402 in human FH) for His reduces dimerization. We also found that a recombinant FHR-B with a duplicated dimerization domain formed stable dimers but lacked functional activity. Overall, FHR-B shows structural and functional similarities with various human FHRs, suggesting convergent evolution between mouse and human FHRs. Furthermore, this study reveals a novel dimerization domain shared by FHR-B and mouse FH and illustrates the importance of dimerization and monomer orientation in FHRs activity. It also underlines notable differences between human and mice FHRs that should be further explored before modeling FHR-associated human diseases in mice.

Structural and evolutionary insights into the functioning of glycoprotein hormones and their receptors.

The neuroendocrine system that comprises the glycoprotein hormones (GpHs) and their receptors is essential for reproduction and metabolism. Each GpH hormone is an αβ heterodimer of cystine-knot proteins and its cognate receptor is a G-protein coupled receptor (GPCR) distinguished by a large leucine-rich-repeat (LRR) extracellular domain that binds the hormone and a class A GPCR transmembrane domain that signals through an associating heterotrimeric G protein. Hence, the receptors are called LRR-containing GPCRs-LGRs. The vertebrate GpHs and LGRs have co-evolved from homologs in the earliest metazoan animals, including sponges and comb jellies, but these are absent from unicellular organisms and plants. The two GpH subunits and accompanying LGR receptor of the nematode Caenorhabditis elegans are representative of the invertebrate evolutionary predecessors of human GpH proteins and their receptors, for example follicle-stimulating hormone (FSH) and the FSH receptor (FSHR). Atomic structures of the human GpHs and their receptors, which have been determined by X-ray crystallography and cryogenic electron microscopy (cryo-EM), inform the evolutionary process and provide a mechanistic understanding of the transmission of biochemical signals of hormone binding at the cell surface to the elicitation of second messengers such as cyclic AMP in the cytoplasm. There is compelling biochemical and cellular evidence for the importance of receptor dimers in GpH signaling in cells; yet, all of the human receptors are monomeric as defined beautifully by cryo-EM. Fortunately, the LGR of C. elegans is a stable dimer and its structure, when analyzed in the context of structural information from the human counterparts, predicts a hypothetical model for functionally relevant dimeric associations of the human GpH receptors.

Role of the Psi Packaging Signal and Dimerization Initiation Sequence in the Organization of Rous Sarcoma Virus Gag-gRNA Co-Condensates.

Retroviral genome selection and virion assembly remain promising targets for novel therapeutic intervention. Recent studies have demonstrated that the Gag proteins of Rous sarcoma virus (RSV) and human immunodeficiency virus type-1 (HIV-1) undergo nuclear trafficking, colocalize with nascent genomic viral RNA (gRNA) at transcription sites, may interact with host transcription factors, and display biophysical properties characteristic of biomolecular condensates. In the present work, we utilized a controlled in vitro condensate assay and advanced imaging approaches to investigate the effects of interactions between RSV Gag condensates and viral and nonviral RNAs on condensate abundance and organization. We observed that the psi (Ψ) packaging signal and the dimerization initiation sequence (DIS) had stabilizing effects on RSV Gag condensates, while RNAs lacking these features promoted or antagonized condensation, depending on local protein concentration and condensate architecture. An RNA containing Ψ, DIS, and the dimerization linkage structure (DLS) that is capable of stable dimer formation was observed to act as a bridge between RSV Gag condensates. These observations suggest additional, condensate-related roles for Gag-Ψ binding, gRNA dimerization, and Gag dimerization/multimerization in gRNA selection and packaging, representing a significant step forward in our understanding of how these interactions collectively facilitate efficient genome packaging.

Stable Dimer Intermediates during Intercluster Reactions of Atomically Precise Nanoclusters

Stable Dimer Intermediates during Intercluster Reactions of Atomically Precise Nanoclusters

Unravelling the Epitaxial Growth Mechanism of Hexagonal and Nanoporous Boron Nitride: A First-Principles Microkinetic Model.

Understanding the chemical and physical mechanisms at play in 2D materials growth is critical for effective process development of methods such as chemical vapor deposition (CVD) as a toolbox for processing more complex nanostructures and 2D materials. A combination of density functional theory and microkinetic modeling is employed to comprehensively investigate the reaction mechanism governing the epitaxial growth of hexagonal boron nitride (hBN) on Ru(0001) from borazine. This analysis encompasses four key stages prior to the formation of the complete hBN overlayer: (i) adsorption, diffusion and deprotonation of borazine, (ii) dimerization and microkinetic modeling (iii) stability of larger borazine polymers and (iv) formation of nanoporous intermediates. In doing so, the exact deprotonation sequence is followed for the first time, illustrating its crucial role for the formation of nanostructures. These findings not only provide insights into the epitaxial growth of hBN and the stability of intermediate overlayers, which are strongly dependent on surface temperature and the amount of precursor exposures, they offer also crucial guidance for producing high-quality hBN monolayers with regular patterns or functionalisation. Importantly, these results align with experimental data and provide a detailed model which explains temperature-dependent, in-situ surface measurements during hBN growth onRu and other substrates.

Infrared Spectroscopy of Ethanethiol Monomers and Dimers at MP2 Level: Characterizing the Dimer Formation and Hydrogen Bond.

Ethanethiol, also known as ethyl mercaptan, is an organosulfur compound that appears as a colorless liquid with a distinctive odor. It has been detected in the interstellar medium, and its self-association has been the subject of a few known experimental studies, where the SH vibrational mode was used. However, unlike the analogous ethanol dimer, the ethanethiol dimer has not been thoroughly explored theoretically. In this study, ethanethiol and dimers were investigated using the MP2 method with various basis sets to determine the properties and stability of these structures. For the monomer, both trans and gauche structures were computed, with the gauche conformer being more stable, consistent with the available data in the literature. Local mode decomposition analysis of monomers showed that the CH2 rocking mode, associated with the CSH bending, is present only for the gauche isomer aligning with the experimental assignments. Furthermore, eight stable dimer configurations were identified and categorized into three groups: trans-trans, gauche-gauche, and trans-gauche isomers. Among these, the trans-gauche isomer was found to be the most stable. Dispersion is the dominant term for the ethanethiol dimer.

Hydration Pattern of Ionic Liquids in the Stabilization of Insulin Dimer: A Computational Perspective

AbstractCholine [Cho]‐based ionic liquids (ILs) are biodegradable and soluble and have shown strong application in the protein stabilization and drug delivery. In this work, the stability of the insulin dimer is investigated in the presence of [Cho]‐based ILs containing three distinct anions (i.e., acetate [OAc], taurate [Tau], and geranate [Ger]). Molecular dynamics (MD) simulations and density functional theory (DFT) calculations explore insulin's stability and structure in the presence of ILs. MD analyses reveal that the insulin dimer is stabilized by non‐covalent interactions, with hydrogen bonds and anions in ILs playing key roles. Among them, [Cho][OAc] ILs show significantly better stabilization than other anions.This is due to the hydration patterns of acetate anion, which can be compared to Hofmeister series and chemical agent effects (i.e., kosmotrope and chaotrope). Further, non‐covalent interactions index and electron density analyses from the atoms‐in‐molecules theory approach are carried out to quantify the strength of non‐covalent interaction in ILs with water clusters (Wn, n = 0–6). Analyses show the significance of water molecules in the stabilization of insulin dimer in the presence of [Cho]‐based ILs. The study elucidates the role of ILs formulation concerning insulin dimers to improve the transdermal and oral drug delivery systems.

Understanding Acute Hemolytic Anemia Severity Through Computational Analysis of G6PDChatham Variant: Designing a New Activator as a Potential Drug

Glucose-6-phosphate dehydrogenase deficiency (G6PDD) is a major enzymatic disease affecting human red blood cells (RBCs), causing hemolytic anemia due to the diminish of the nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) synthesis and altered redox balance within erythrocytes. This study sought to correct the defect in G6PDChatham (Ala355Thr) caused by the loss of interactions (hydrogen bonds and salt bridges) by docking the AG1 molecule at the dimer interface, thus restoring these lost interactions. The enzyme conformation was then analyzed before and after AG1 binding using molecular dynamics simulation (MDS). The reasons behind the severity of acute hemolytic anemia (AHA) were explained using several parameters, such as root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), hydrogen bonds, salt bridges, radius of gyration (Rg), solvent accessible surface area (SASA), and covariance matrix analysis. Structural alterations in G6PDChatham, including the absence of interactions in a key region of the variant structure, can significantly impact protein stability and function, subsequently contributing to disease severity. Upon AG1 binding, these missing interactions were resorted to correct the structural defect of the variant. This restoration improves dimer stability and restores G6PD function. To develop new G6PD activators, several new analogues (SY7, SY8, SY9, and SY10) were rationally developed by substituting the linker region of the AG1 structure with other functional groups using the Avogadro software. These compounds were successfully synthesized and docked with G6PDChatham where the best binding affinity ranged between -8.0 and -9.1 kcal/mol. SY8, a promising G6PD activator, is predicted to be easily metabolized and excreted, making it less likely to cause toxicity. Its high drug score, drug-likeness, and favorable safety profile make it a strong candidate for synthesis and cellular testing. The toxicity risk assessment supported the overall drug score, increasing confidence in finding additional small-molecule activators for G6PDD disorder. Amidst the absence of effective treatments, such discovery hopes to improve the lives of those with AHA by assisting the development of appropriate pharmaceuticals for G6PDD.

Transient interdomain interactions modulate the monomeric structural ensemble and self-assembly of Huntingtin Exon 1.

Polyglutamine expansion (≥ 36 residues) within the N-terminal exon-1 of Huntingtin (Httex1) leads to Huntington's disease, a neurodegenerative condition marked by the presence of intranuclear Htt inclusions. Notably, the polyglutamine tract in Httex1 is flanked by an N-terminal coiled-coil domain - N17 (17 amino acids), which undergoes self-association to promote the formation of soluble Httex1 oligomers and brings the aggregation-prone polyQ tracts in close spatial proximity. However, the mechanisms underlying the subsequent conversion of soluble oligomers into insoluble β-rich aggregates with increasing polyQ length, remain unclear. Current knowledge suggests that expansion of the polyQ tract increases its helicity, and this favors its oligomerization and aggregation. In addition, studies utilizing photocrosslinking, conformation-specific antibodies and a stable coiled-coil heterotetrametric system fused to polyQ indicate that domain "cross-talk" (i.e., interdomain interactions) may play a role in the emergence of toxic conformations and the conversion of Httex1 oligomers into fibrillar aggregates. Here, we performed extensive atomistic molecular dynamics (MD) simulations (aggregate time ∼ 0.7 ms) to uncover the interplay between structural transformation and domain "cross-talk" on the conformational ensemble and oligomerization landscape of Httex1. Notably, our MD-derived ensembles of N17-polyQ monomers validated against 13 C NMR chemical shifts indicated that in addition to elevated α- helicity, polyQ expansion also favors transient, interdomain (N17-polyQ) interactions which result in the emergence of β-sheet conformations. Further, interdomain interactions competed with increased polyQ tract α-helicity to modulate the stability of N17-mediated dimers and thereby promoted a heterogenous dimerization landscape. Finally, we observed that the C-terminal proline-rich domain (PRD) promoted condensation of Httex1 through self-interactions involving its P 10 /P 11 tracts while also interacting with N17 to suppress its α-helicity. In summary, our study demonstrates a significant role for domain "cross-talk" in modulating the monomeric structural ensemble and self-assembly of Httex1.

Dimerization of ADAR1 modulates site-specificity of RNA editing

Adenosine-to-inosine editing is catalyzed by adenosine deaminases acting on RNA (ADARs) in double-stranded RNA (dsRNA) regions. Although three ADARs exist in mammals, ADAR1 is responsible for the vast majority of the editing events and acts on thousands of sites in the human transcriptome. ADAR1 has been proposed to form a stable homodimer and dimerization is suggested to be important for editing activity. In the absence of a structural basis for the dimerization of ADAR1, and without a way to prevent dimer formation, the effect of dimerization on enzyme activity or site specificity has remained elusive. Here, we report on the structural analysis of the third double-stranded RNA-binding domain of ADAR1 (dsRBD3), which reveals stable dimer formation through a large inter-domain interface. Exploiting these structural insights, we engineered an interface-mutant disrupting ADAR1-dsRBD3 dimerization. Notably, dimerization disruption did not abrogate ADAR1 editing activity but intricately affected editing efficiency at selected sites. This suggests a complex role for dimerization in the selection of editing sites by ADARs, and makes dimerization a potential target for modulating ADAR1 editing activity.

Dimerization of the deaminase domain and locking interactions with Cas9 boost base editing efficiency in ABE8e.

CRISPR-based DNA adenine base editors (ABEs) hold remarkable promises to address human genetic diseases caused by point mutations. ABEs were developed by combining CRISPR-Cas9 with a transfer RNA (tRNA) adenosine deaminase enzyme and through directed evolution, conferring the ability to deaminate DNA. However, the molecular mechanisms driving the efficient DNA deamination in the evolved ABEs remain unresolved. Here, extensive molecular simulations and biochemical experiments reveal the biophysical basis behind the astonishing base editing efficiency of ABE8e, the most efficient ABE to date. We demonstrate that the ABE8e's DNA deaminase domain, TadA8e, forms remarkably stable dimers compared to its tRNA-deaminating progenitor and that the strength of TadA dimerization is crucial for DNA deamination. The TadA8e dimer forms robust interactions involving its R98 and R129 residues, the RuvC domain of Cas9 and the DNA. These locking interactions are exclusive to ABE8e, distinguishing it from its predecessor, ABE7.10, and are indispensable to boost DNA deamination. Additionally, we identify three critical residues that drive the evolution of ABE8e toward improved base editing by balancing the enzyme's activity and stability, reinforcing the TadA8e dimer and improving the ABE8e's functionality. These insights offer new directions to engineer superior ABEs, advancing the design of safer precision genome editing tools.

Amorphous Titanium Dioxide Nanoparticles and Their Unexpected Fragmentation in MALDI-TOF/MS.

Amorphous 3 nm large ultrasmall (usTiO2) and 7 nm large anatase (nTiO2) nanoparticles (NPs) were successfully prepared and characterized by TEM, FTIR, DRX, UV-vis, and DLS techniques. The MALDI-TOF/MS was shown to be effective in assessing the surface chemistry but fragmentation processes precluded its use for evaluation of particle size distribution. In fact, the laser causes the fragmentation not only of amorphous TiO2 NPs but also of the material subjected to heat treatment and crystallization at 450 °C for 4 h upon interaction with the DHB matrix and TFA ionizing agent. No significant difference could be observed in the spectrum by varying the particle size, indicating the high stability of the TiO2 dimer and its low aggregates in the gaseous phase. In short, MALDI-TOF/MS is effective for the direct analysis of nanoparticle surfaces, especially the interaction of functionalizing molecular species with the inorganic components, which in combination with the other techniques demonstrated to be ideal for the detailed characterization of nanomaterials.

Conformational Dynamics of Hemoglobin in Solution and the Gas Phase Elucidated by Mass Spectrometry.

Solution and gas-phase measurements can provide valuable insights into biomolecular conformational dynamics. By comparing the data from such experiments, it is possible to elucidate the nature of the interactions governing a biomolecule's stability. Here, we measured human, bovine, and porcine hemoglobin stability in solution and the gas phase using collision-induced dissociation, collision-induced unfolding, surface-induced dissociation, and temperature-controlled nanoelectrospray mass spectrometry. Hemoglobin dimer and tetramer stability in solution and gas phases did not correlate, likely due to differences in the composition of positive and negative amino acids on the surface of these molecules. Specifically, the absence of Lys-116 on the β-subunit makes it easier for the human hemoglobin dimer to dissociate in the gas phase. However, the presence of Lys-60 makes the subunit more rigid thus it cannot unfold to the same extent as the other hemoglobin. Hemoglobin tetramers of different origins had similar stability in the gas phase, as there was no difference in the composition of charged amino acids at the tetramer interface. These results highlight how temperature-controlled mass spectrometry and collision-induced unfolding can elucidate the structural reasons behind differences in the gas-phase and solution stability of protein complexes.

The Investigation of Fe─F Bond Chemistry on Structural Stability for Highly Durable Layered Na2FePO4F Cathode

AbstractLayered iron (Fe) ‐based fluorophosphates, Na2FePO4F (NFPF) stands for a cost‐effective and voltage‐advantageous cathode material for sodium‐ion batteries. Nevertheless, the lack of stability imposes constraints on its development and the decay mechanism remains shrouded in ambiguity. Herein, this work proposes the breakup of Fe─F bond in octahedral dimer accountable for the dissolution of redox centers and the formation of electrochemically inert phase, ultimately leading to the deterioration of electrochemical stability. To verify and address this, Boron (B) atoms situated in interstitial positions of PO4 tetrahedra appearing trigonal BO3 can be specifically targeted to enhance bond covalency and tailor electronic rearrangements at Fe─F bonds, thus stabilizing the octahedral dimer structure. This also facilitates rapid Na+ diffusion dynamics and accelerated electronic conductivity. As expected, NFPF‐B exhibits an ultra‐high discharge specific capacity (118.34 mAh g−1 at 0.1C) and excellent long‐term durability (capacity retention of 91.9% after 1000 cycles). The stability of the octahedra dimer is underscored by minimal volume change (2.9%) within the two‐stage biphase reaction of sodium storage mechanism. This work elucidates the enduring degradation mechanism of NFPF from octahedral dimers and offer theoretical guidance for Fe‐based cathode materials with prolonged stability.

Identification of a Hidden, Highly Aggregation-Prone Intermediate of Full-Length TDP-43 That Triggers its Misfolding and Amyloid Aggregation.

In cells, TDP-43 is a crucial protein that can form harmful amyloid aggregates linked to fatal and incurable human neurodegenerative disorders. Normally, TDP-43 exists in a smaller soluble native state that prevents aggregation. However, aging and stress can destabilize this native state, leading to the formation of disease-causing amyloid aggregates via the formation of partially unfolded, high-energy intermediates with a greater tendency to aggregate. These intermediates are crucial in the early stages of amyloid formation and are challenging to study due to their low stability. Understanding the structure of these early aggregation-prone states of TDP-43 is essential for designing effective treatments for TDP-43 proteinopathies. Targeting these initial intermediates could be more effective than focusing on fully formed amyloid aggregates. By disrupting the aggregation process at this early stage, we may be able to prevent the progression of diseases related to TDP-43 aggregation. Hence, we decided to uncover the hidden, high-energy intermediates in equilibrium with the native states of TDP-43 by modulating the thermodynamic stability of the soluble native dimer (N form) and monomeric molten globular state (MG form) of full-length TDP-43. The thermodynamic modulation performed in the current study successfully revealed the highly aggregation-prone intermediate of full-length TDP-43, i.e., PUF. Moreover, we observed that along with high aggregation propensity, the aggregation kinetics and mechanisms of PUF differ from previously identified intermediates of full-length TDP-43 (the MG and I forms). The information regarding the initial aggregation-prone state of full-length TDP-43 could lead to therapies for amyloid diseases by halting early protein aggregation.

Oocyte death is triggered by the stabilization of TAp63α dimers in response to cisplatin

The TAp63α protein is highly expressed in primordial follicle oocytes, where it typically exists in an inactive dimeric form. Upon DNA damage, TAp63α undergoes hyperphosphorylation, transitioning from a dimeric to a tetrameric structure, which initiates oocyte apoptosis by upregulating pro-apoptotic gene. Our results demonstrate that cisplatin, an alkylating anti-cancer agent, predominantly produced the TAp63α dimer rather than the tetramer. We further observed that TAp63α protein accumulation occurred in primordial follicle oocytes following cisplatin treatment, and this accumulation was significantly reduced by cycloheximide, a protein synthesis inhibitor. These findings suggest that TAp63α accumulation is driven primarily by de novo protein synthesis in response to DNA damage. Notably, cycloheximide protected oocytes from cisplatin-induced apoptosis, as evidenced by reduced levels of both PUMA, a known pro-apoptotic target gene of TAp63α, and TAp63α itself. Additionally, TAp63α turnover appears to be regulated by ubiquitination and proteasome degradation, as evidenced by TAp63α accumulation without oocyte death when treated with PYR-41, a pharmacological inhibitor. However, when TAp63α was stabilized by PYR-41 and subsequently activated by cisplatin, oocyte death occurred, marked by increased γH2AX and Cleaved PARP. Moreover, the Casein kinase 1 inhibitor PF-670462 effectively blocked cisplatin-induced oocyte death, indicating that CK1-mediated phosphorylation is essential for TAp63α activation, even in the absence of tetramer formation. The ATR inhibitor BEZ235 prevented cisplatin-induced TAp63α accumulation, suggesting that TAp63α accumulation precedes its phosphorylation-driven activation. Collectively, our study reveals a novel mechanism of cisplatin-induced apoptosis in primordial follicle oocyte through TAp63α stabilization and accumulation, independent of tetramerization.

Conformational Differences in the Light Chain Constant Domain of Immunoglobulin G and Free Light Chain May Influence Proteolysis in AL Amyloidosis

Immunoglobulin light chain amyloidosis (AL) is a life-threatening disease caused by the deposition of light chain (LC) and its fragments containing variable (VL) and portions of constant (CL) domains. AL patients feature either monoclonal free LCs (FLCs) circulating as covalent and noncovalent homodimers, or monoclonal immunoglobulin (Ig) wherein the LC and heavy chain (HC) form disulfide-linked heterodimers, or both. The role of full-length Ig in AL amyloidosis is unclear as prior studies focused on FLC or VL domain. We used a mammalian cell-based expression system to generate four AL patient-derived full-length IgGs, two non-AL IgG controls, and six corresponding FLC proteins derived from an IGLV6-57 germline precursor. Comparison of proteins' secondary structure, thermal stability, proteolytic susceptibility, and disulfide link reduction suggested the importance of local vs. global conformational stability. Analysis of IgGs vs. corresponding FLCs using hydrogen-deuterium exchange mass spectrometry revealed major differences in the local conformation/dynamics of the CL domain. In all IgGs vs. FLCs, segments containing β-strand and α-helix βAC-αACBC were more dynamic/exposed while segment βDC-βEC was less dynamic/exposed. Notably, these segments overlapped proteolysis-prone regions whose in vivo cleavage generates LC fragments found in AL deposits. Altogether, the results suggest that preferential cleavage in segments βAC-αACBC of FLC or βDC-βEC of LC in IgG helps generate amyloid protein precursors. We propose that protecting these segments using small-molecule stabilizers, which bind to the interfacial cavities CL-CL in FLC and/or CL-CH1 in IgG, is a potential therapeutic strategy to complement current approaches targeting VL-VL or VL-CL stabilization of LC dimer.

Molecular insights into the structure and function of the Staphylococcus aureus fatty acid kinase

Gram-positive bacteria utilize a Fatty Acid Kinase (FAK) complex to harvest fatty acids from the environment. This complex consists of the fatty acid kinase, FakA, and an acyl carrier protein, FakB, and is known to impact virulence and disease outcomes. Despite some recent studies, there remain many outstanding questions as to the enzymatic mechanism and structure of FAK. To better address this knowledge gap, we used a combination of modeling, biochemical, and cell-based approaches to build on prior proposed models and identify critical details of FAK activity. Using bio-layer interferometry, we demonstrated nanomolar affinity between FakA and FakB which also indicates that FakA is dimer when binding FakB. Additionally, targeted mutagenesis of the FakA Middle domain demonstrates it possesses a metal binding pocket that is critical for FakA dimer stability and FAK function invitro and invivo. Lastly, we solved structures of the apo and ligand-bound FakA kinase domain to capture the molecular changes in the protein following ATP binding and hydrolysis. Together, these data provide critical insight into the structure and function of the FAK complex which is essential for understanding its mechanism.