Journal of Molecular Biology

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  • Structures of DegQ from Legionella pneumophila define distinct ON and OFF states
    [Jul 2015]

    Publication date: Available online 20 July 2015
    Source:Journal of Molecular Biology

    Author(s): Alexander Schubert, Robert Wrase, Rolf Hilgenfeld, Guido Hansen

    HtrA family proteins play important roles in protein-quality control processes in the bacterial periplasm. A common feature of all members of this family is their modular organisation comprising a chymotrypsin-like protease domain and at least one PDZ domain. All characterized HtrA proteins assemble into complex oligomers consisting of typically 3 to 24 monomers, which allow a tight regulation of proteolytic activity. Here, we provide evidence that the assembly of proteolytically active, higher-order complexes of DegQ from Legionella pneumophila is triggered by the binding of substrate-derived peptides. Crystal structures of inactive 3-mers and active 12-mers of DegQ reveal molecular details of elements of a conserved allosteric activation cascade that defines distinct protease ON and OFF states. Results from DegQLp variants harbouring structure-based amino-acid substitutions indicate that peptide binding to the PDZ1 domain is critical for proteolytic activity but not for the formation of higher-order oligomers. Combining structural, mutagenesis and biochemical data, we show that in contrast to the proteolytic activity, the chaperone function of DegQ is not affected by the state of the activation cascade.
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    Categories: Journal Articles
  • Acidic residues in the Hfq chaperone increase the selectivity of sRNA binding and annealing
    [Jul 2015]

    Publication date: Available online 18 July 2015
    Source:Journal of Molecular Biology

    Author(s): Subrata Panja, Andrew Santiago-Frangos, Daniel J. Schu, Susan Gottesman, Sarah A. Woodson

    Hfq facilitates gene regulation by small non-coding RNAs (sRNAs), thereby affecting bacterial attributes such as biofilm formation and virulence. E. coli Hfq recognizes specific U-rich and AAN motifs in sRNAs and target mRNAs, after which an arginine patch on the rim promotes base pairing between their complementary sequences. In the cell, Hfq must discriminate between many similar RNAs. Here, we report that acidic amino acids lining the sRNA binding channel between the inner pore and rim of the Hfq hexamer contribute to the selectivity of Hfq’s chaperone activity. RNase footprinting, in vitro binding and stopped-flow fluorescence annealing assays showed that alanine substitution of D9, E18 or E37 strengthened RNA interactions with the rim of Hfq and increased annealing of non-specific or U-tailed RNA oligomers. Although the mutants were less able than WT Hfq to anneal sRNAs with wild type rpoS mRNA, the D9A mutation bypassed recruitment of Hfq to an (AAN)4 motif in rpoS, both in vitro and in vivo. These results suggest that acidic residues normally modulate access of RNAs to the arginine patch. We propose that this selectivity limits indiscriminate target selection by E. coli Hfq, and enforces binding modes that favor genuine sRNA and mRNA pairs.
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  • The modulatable stem cell niche: Tissue interactions during hair and feather follicle regeneration
    [Jul 2015]

    Publication date: Available online 18 July 2015
    Source:Journal of Molecular Biology

    Author(s): Chih-Chiang Chen, Maksim V. Plikus, Pin-Chi Tang, Randall B. Widelitz, Cheng Ming Chuong

    Hair and feathers are unique because 1) their stem cells are contained within a follicle structure, 2) they undergo cyclic regeneration repetitively throughout life, 3) regeneration occurs physiologically in healthy individuals and 4) regeneration is also induced in response to injury. Precise control of this cyclic regeneration process is essential for maintaining the homeostasis of living organisms. While stem cells are regulated by the intra-follicle adjacent micro-environmental niche, this niche is also modulated dynamically by extra-follicular macro-environmental signals, allowing stem cells to adapt to a larger changing environment and physiological needs. Here we review several examples of macro-environments that communicate with the follicles: intradermal adipose tissue, innate immune system, sex hormones, aging, circadian rhythm and seasonal rhythms. Related diseases are also discussed. Unveiling the mechanisms of how stem cell niches are modulated provides clues for regenerative medicine. Given that stem cells are hard to manipulate, focusing translational therapeutic applications at the environments appears to be a more practical approach.
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    Categories: Journal Articles
  • Editorial Board
    [Jul 2015]

    Publication date: 17 July 2015
    Source:Journal of Molecular Biology, Volume 427, Issue 14









    Categories: Journal Articles
  • Contents List
    [Jul 2015]

    Publication date: 17 July 2015
    Source:Journal of Molecular Biology, Volume 427, Issue 14









    Categories: Journal Articles
  • Small-Molecule Transport by CarO, an Abundant Eight-Stranded β-Barrel Outer Membrane Protein from Acinetobacter baumannii
    [Jul 2015]

    Publication date: 17 July 2015
    Source:Journal of Molecular Biology, Volume 427, Issue 14

    Author(s): Michael Zahn, Tommaso D'Agostino, Elif Eren, Arnaud Baslé, Matteo Ceccarelli, Bert van den Berg

    Outer membrane (OM) β-barrel proteins composed of 12–18 β-strands mediate cellular entry of small molecules in Gram-negative bacteria. Small OM proteins with barrels of 10 strands or less are not known to transport small molecules. CarO (carbapenem-associated outer membrane protein) from Acinetobacter baumannii is a small OM protein that has been implicated in the uptake of ornithine and carbapenem antibiotics. Here we report crystal structures of three isoforms of CarO. The structures are very similar and show a monomeric eight-stranded barrel lacking an open channel. CarO has a substantial extracellular domain resembling a glove that contains all the divergent residues between the different isoforms. Liposome swelling experiments demonstrate that full-length CarO and a “loop-less” truncation mutant mediate small-molecule uptake at low levels but that they are unlikely to mediate passage of carbapenem antibiotics. These results are confirmed by biased molecular dynamics simulations that allowed us to quantitatively model the transport of selected small molecules.
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  • Minimal Hammerhead Ribozymes with Uncompromised Catalytic Activity
    [Jul 2015]

    Publication date: 17 July 2015
    Source:Journal of Molecular Biology, Volume 427, Issue 14

    Author(s): Sara M. O'Rourke, William Estell, William G. Scott

    We report here that a single additional trans-Hoogsteen base-pairing interaction in the minimal hammerhead ribozyme transforms an RNA sequence possessing typically modest catalytic activity into one possessing greatly enhanced catalytic activity that is instead typical of full-length natural hammerhead RNAs that have additional extensive tertiary contact interactions. Formation of this additional base-pairing interaction requires only that the substrate RNA sequence contains a U at a position seven nucleotides 3′ to the cleavage site. No additions or changes are required in the minimal hammerhead ribozyme enzyme strand sequence (providing that the naturally occurring GUGA tetraloop of Stem II is maintained). This finding unambiguously demonstrates that a single Hoogsteen base-pairing interaction, in full-length hammerheads possessing this interaction, is sufficient for stabilizing the ribozyme active site, including alignment of the attacking nucleophile for the required inline hammerhead ribozyme reaction mechanism. This finding also implies that the idiosyncratic arrays of additional tertiary contacts observed in all naturally occurring full-length hammerhead sequences have evolved to prevent deleterious alternative pairing interactions within the context of the variety of natural sequences arising in vivo. Finally, this finding greatly simplifies and rationalizes the design of fast-cleaving engineered synthetic ribozymes as RNA nucleolytic reagents and as subjects for enzyme kinetics and mechanistic investigations.
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  • Conformational Changes of the Clamp of the Protein Translocation ATPase SecA
    [Jul 2015]

    Publication date: 17 July 2015
    Source:Journal of Molecular Biology, Volume 427, Issue 14

    Author(s): Yu Chen, Benedikt W. Bauer, Tom A. Rapoport, James C. Gumbart

    Post-translational protein translocation across the bacterial plasma membrane is mediated by the interplay of the SecA ATPase and the protein-conducting SecY channel. SecA consists of several domains, including two nucleotide-binding domains (NBD1 and NBD2), a polypeptide cross-linking domain (PPXD), a helical scaffold domain (HSD), and a helical wing domain (HWD). PPXD, HSD, and NBD2 form a clamp that positions the polypeptide substrate above the channel so that it can be pushed into the channel by a two-helix finger of the HSD. How the substrate is accommodated in the clamp during translocation is unclear. Here, we report a crystal structure of Thermotoga maritima SecA at 1.9Å resolution. Structural analysis and free-energy calculations indicate that the new structure represents an intermediate state during the transition of the clamp from an open to a closed conformation. Molecular dynamics simulations show that closure of the clamp occurs in two phases, an initial movement of PPXD, HSD, and HWD as a unit, followed by a movement of PPXD alone toward NBD2. Simulations in the presence of a polypeptide chain show that the substrate associates with the back of the clamp by dynamic hydrogen bonding and that the clamp is laterally closed by a conserved loop of the PPXD. Mutational disruption of clamp opening or closure abolishes protein translocation. These results suggest how conformational changes of SecA allow substrate binding and movement during protein translocation.
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  • A Direct Interaction with RNA Dramatically Enhances the Catalytic Activity of the HIV-1 Protease In Vitro
    [Jul 2015]

    Publication date: 17 July 2015
    Source:Journal of Molecular Biology, Volume 427, Issue 14

    Author(s): Marc Potempa, Ellen Nalivaika, Debra Ragland, Sook-Kyung Lee, Celia A. Schiffer, Ronald Swanstrom

    Though the steps of human immunodeficiency virus type 1 (HIV-1) virion maturation are well documented, the mechanisms regulating the proteolysis of the Gag and Gag-Pro-Pol polyproteins by the HIV-1 protease (PR) remain obscure. One proposed mechanism argues that the maturation intermediate p15NC must interact with RNA for efficient cleavage by the PR. We investigated this phenomenon and found that processing of multiple substrates by the HIV-1 PR was enhanced in the presence of RNA. The acceleration of proteolysis occurred independently from the substrate's ability to interact with nucleic acid, indicating that a direct interaction between substrate and RNA is not necessary for enhancement. Gel-shift assays demonstrated the HIV-1 PR is capable of interacting with nucleic acids, suggesting that RNA accelerates processing reactions by interacting with the PR rather than the substrate. All HIV-1 PRs examined have this ability; however, the HIV-2 PR does not interact with RNA and does not exhibit enhanced catalytic activity in the presence of RNA. No specific sequence or structure was required in the RNA for a productive interaction with the HIV-1 PR, which appears to be principally, though not exclusively, driven by electrostatic forces. For a peptide substrate, RNA increased the kinetic efficiency of the HIV-1 PR by an order of magnitude, affecting both turnover rate (k cat) and substrate affinity (K m). These results suggest that an allosteric binding site exists on the HIV-1 PR and that HIV-1 PR activity during maturation could be regulated in part by the juxtaposition of the enzyme with virion-packaged RNA.
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  • CLASP2 Has Two Distinct TOG Domains That Contribute Differently to Microtubule Dynamics
    [Jul 2015]

    Publication date: 17 July 2015
    Source:Journal of Molecular Biology, Volume 427, Issue 14

    Author(s): Takahisa Maki, Ashley D. Grimaldi, Sotaro Fuchigami, Irina Kaverina, Ikuko Hayashi

    CLIP-associated proteins CLASPs are mammalian microtubule (MT) plus-end tracking proteins (+TIPs) that promote MT rescue in vivo. Their plus-end localization is dependent on other +TIPs, EB1 and CLIP-170, but in the leading edge of the cell, CLASPs display lattice-binding activity. MT association of CLASPs is suggested to be regulated by multiple TOG (tumor overexpressed gene) domains and by the serine-arginine (SR)-rich region, which contains binding sites for EB1. Here, we report the crystal structures of the two TOG domains of CLASP2. Both domains consist of six HEAT repeats, which are similar to the canonical paddle-like tubulin-binding TOG domains, but have arched conformations. The degrees and directions of curvature are different between the two TOG domains, implying that they have distinct roles in MT binding. Using biochemical, molecular modeling and cell biological analyses, we have investigated the interactions between the TOG domains and αβ-tubulin and found that each domain associates differently with αβ-tubulin. Our findings suggest that, by varying the degrees of domain curvature, the TOG domains may distinguish the structural conformation of the tubulin dimer, discriminate between different states of MT dynamic instability and thereby function differentially as stabilizers of MTs.
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  • Negative Epistasis and Evolvability in TEM-1 β-Lactamase—The Thin Line between an Enzyme's Conformational Freedom and Disorder
    [Jul 2015]

    Publication date: 17 July 2015
    Source:Journal of Molecular Biology, Volume 427, Issue 14

    Author(s): Eynat Dellus-Gur, Mikael Elias, Emilia Caselli, Fabio Prati, Merijn L.M. Salverda, J. Arjan G.M. de Visser, James S. Fraser, Dan S. Tawfik

    Epistasis is a key factor in evolution since it determines which combinations of mutations provide adaptive solutions and which mutational pathways toward these solutions are accessible by natural selection. There is growing evidence for the pervasiveness of sign epistasis—a complete reversion of mutational effects, particularly in protein evolution—yet its molecular basis remains poorly understood. We describe the structural basis of sign epistasis between G238S and R164S, two adaptive mutations in TEM-1 β-lactamase— an enzyme that endows antibiotics resistance. Separated by 10Å, these mutations initiate two separate trajectories toward increased hydrolysis rates and resistance toward second and third-generation cephalosporins antibiotics. Both mutations allow the enzyme's active site to adopt alternative conformations and accommodate the new antibiotics. By solving the corresponding set of crystal structures, we found that R164S causes local disorder whereas G238S induces discrete conformations. When combined, the mutations in 238 and 164 induce local disorder whereby nonproductive conformations that perturb the enzyme's catalytic preorganization dominate. Specifically, Asn170 that coordinates the deacylating water molecule is misaligned, in both the free form and the inhibitor-bound double mutant. This local disorder is not restored by stabilizing global suppressor mutations and thus leads to an evolutionary cul-de-sac. Conformational dynamism therefore underlines the reshaping potential of protein's structures and functions but also limits protein evolvability because of the fragility of the interactions networks that maintain protein structures.
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  • A regulated, ubiquitin-independent degron in IκBα
    [Jul 2015]

    Publication date: Available online 17 July 2015
    Source:Journal of Molecular Biology

    Author(s): Karen T. Fortmann, Russell D. Lewis, Kim A. Ngo, Riku Fagerlund, Alexander Hoffmann

    Whereas ubiquitin-dependent degrons have been characterized in some detail, how proteins may be targeted to ubiquitin-independent proteasomal degradation remains unclear. Here we show that IκBα contains a ubiquitin-independent degron whose activity is portable to heterologous proteins such as the globular protein GFP via a proteasome-dependent, ubiquitin-independent, non-lysosomal pathway. The ubiquitin-independent degradation signal resides in a 11 amino acid sequence, which is not only sufficient but also required for IκBα’s short half-life. Finally, we show that this degron’s activity is regulated by the interaction with NFκB, which controls its solvent exposure, and we demonstrate that this regulation of the degron’s activity is critical for IκBα’s signaling functions.
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  • Brainless But Multi-Headed: Decision-Making by the Acellular Slime Mould Physarum Polycephalum
    [Jul 2015]

    Publication date: Available online 17 July 2015
    Source:Journal of Molecular Biology

    Author(s): Madeleine Beekman, Tanya Latty

    Because of its peculiar biology and the ease with which it can be cultured, the acellular slime mould Physarum polycephalum has long been a model organism in a range of disciplines. Due to its macroscopic, syncytial nature, it is no surprise it has been a favourite amongst cell biologists. Its inclusion in the experimental tool kit of behavioural ecologists is much more recent. These recent studies have certainly paid off. They have shown that for an organism that lacks a brain or central nervous system P. polycephalum shows rather complex behaviour. For example it is capable of finding the shortest path through a maze, can construct networks as efficient as those designed by humans, solve computationally difficult puzzles, makes multi-objective foraging decisions, balances its nutrient intake and even behaves irrationally. Are the slime mould’s achievements simply ‘cute’, worthy of mentioning in passing, but nothing to take too seriously? Or do they hint at the fundamental processes underlying all decision-making? We will address this question after reviewing the decision-making abilities of the slime mould.
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  • Structural and functional characterization of a novel family GH115 4-O-Methyl-α-glucuronidase with specificity for decorated arabinogalactans
    [Jul 2015]

    Publication date: Available online 14 July 2015
    Source:Journal of Molecular Biology

    Author(s): Friso Aalbers, Johan P. Turkenburg, Gideon J. Davies, Lubbert Dijkhuizen, Alicia Lammerts van Bueren

    Glycoside hydrolases are clustered into families based on amino acid sequence similarities, and belonging to a particular family can infer biological activity of an enzyme. Family GH115 contains α-glucuronidases where several members have been shown to hydrolyze terminal α-1,2-linked glucuronic acid and 4-O-methylated glucuronic acid from the plant cell wall polysaccharide glucuronoxylan. Other GH115 enzymes show no activity on glucuronoxylan, and therefore it has been proposed that family GH115 may be a poly-specific family. In this study we reveal that a putative periplasmic GH115 from the human gut symbiont Bacteroides thetaiotaomicron, BtGH115A, hydrolyzes terminal 4-O-methyl-gluruconic acid residues from decorated arabinogalactan isolated from acacia tree. The 3-dimensional structure of BtGH115A reveals that BtGH115A has the same domain architecture as the other structurally characterized member of this family, BoAgu115A, however the C-terminal module is located in different positions in each enzyme; in BoAgu115A it facilitates dimerization via interactions with the catalytic domain of the adjacent polypeptide chain while in BtGH115A it associates with the catalytic domain in the same polypeptide chain. Phylogenetic analysis of GH115 amino sequences divide the family into distinct clades which may distinguish different substrate specificities. Finally, we show that BtGH115A α-glucuronidase activity is necessary for the sequential digestion of branched galactans from acacia gum by a galactan-β-1,3-galactosidase from family GH43, however, while B. thetaiotaomicron grows on larch wood arabinogalactan, the bacterium is not able to metabolize acacia gum arabinogalactan, suggesting that BtGH115A is involved in degradation of arabinogalactan fragments liberated by other microbial species in the gastrointestinal tract.
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    Categories: Journal Articles
  • The contribution of missense mutations in core and Rim residues of protein-protein interfaces to human disease
    [Jul 2015]

    Publication date: Available online 11 July 2015
    Source:Journal of Molecular Biology

    Author(s): Alessia David, Michael J. Sternberg

    Missense mutations at protein-protein interaction (PPIs) sites, called interfaces, are important contributors to human disease. Interfaces are non-uniform surface areas characterized by two main regions, ‘core’ and ‘rim’, which differ in terms of evolutionary conservation and physico-chemical properties. Moreover, within interfaces, only a small subset of residues (‘hot spots’) is crucial for the binding free energy of the protein-protein complex. We performed a large-scale structural analysis of human single amino acid variations (SAVs) and demonstrated that disease-causing mutations are preferentially located within the interface core, as opposed to the rim (p< 0.01). In contrast, the interface rim is significantly enriched in polymorphisms, similar to the remaining non-interacting surface. Energetic hot spots tend to be enriched in disease-causing mutations compared to non-hot spots (p=0.05), regardless of their occurrence in core or rim residues. For individual amino acids, the frequency of substitution into a polymorphism or disease-causing mutation differed to other amino acids and was related to its structural location, as was the type of physico-chemical change introduced by the SAV. In conclusion, this study demonstrated the different distribution and properties of disease-causing SAVs and polymorphisms within different structural regions and in relation to the energetic contribution of amino acid in protein-protein interfaces, thus highlighting the importance of a structural system biology approach for predicting the effect of SAVs.
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    Categories: Journal Articles
  • Emerging Roles for Maf1 beyond the Regulation of RNA Polymerase III Activity
    [Jul 2015]

    Publication date: Available online 11 July 2015
    Source:Journal of Molecular Biology

    Author(s): Akshat Khanna, Ajay Pradhan, Sean P. Curran

    Maf1 was first identified in yeast, and studies in metazoans have primarily focused on examining its role in the repression of transcription that is dependent on RNA polymerase III. Recent work has revealed a novel and conserved function for Maf1 in the maintenance of intracellular lipid pools in Caenorhabditis elegans, mice, and cancer cell lines. Although additional Maf1 targets are likely, they have not been identified, and these recent findings begin to define specific activities for Maf1 in multicellular organisms beyond the regulation of RNA polymerase III transcription and suggest that Maf1 plays a more diverse role in organismal physiology. We will discuss these newly defined physiological roles of Maf1 that point to its placement as an important new player in lipid metabolism with implications in human metabolic diseases such as obesity and cancer, which display prominent defects in lipid homeostasis.
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  • Erratum to “Discrete Molecular Dynamics Study of Oligomer Formation by N-Terminally Truncated Amyloid β-Protein” [J. Mol. Biol. 425 (2013) 2260–2275]
    [Jul 2015]

    Publication date: Available online 10 July 2015
    Source:Journal of Molecular Biology

    Author(s): Derya Meral, Brigita Urbanc







    Categories: Journal Articles
  • Metavinculin tunes the flexibility and the architecture of vinculin induced bundles of actin filaments
    [Jul 2015]

    Publication date: Available online 10 July 2015
    Source:Journal of Molecular Biology

    Author(s): Zeynep A. Oztug Durer, Rebecca M. McGillivary, Hyeran Kang, W. Austin Elam, Christina L. Vizcarra, Dorit Hanein, Enrique M. De La Cruz, Emil Reisler, Margot E. Quinlan

    Vinculin is an abundant protein found at cell-cell and cell-extracellular matrix junctions. In muscles, a longer splice-isoform of vinculin, metavinculin, is also expressed. The metavinculin-specific insert is part of the C-terminal tail domain, the actin-binding site of both isoforms. Mutations in the metavinculin-specific insert are linked to heart disease such as dilated cardiomyopathies. Vinculin tail domain (VT) both binds and bundles actin filaments. Metavinculin tail domain (MVT) binds actin filaments in a similar orientation but does not bundle filaments. Recently, MVT was reported to sever actin filaments. In this work, we asked how MVT influences F-actin alone or in combination with VT. Cosedimentation and limited proteolysis experiments indicated a similar actin binding affinity and mode for both VT and MVT. In real time TIRF microscopy experiments MVT’s severing activity was negligible. Instead, we found that MVT binding caused a two-fold reduction in F-actin’s bending persistence length and increased susceptibility to breakage. Perhaps MVT allows the load of muscle contraction to act as a signal to reorganize actin filaments. Using mutagenesis and site-directed labeling with fluorescence probes, we determined that MVT alters actin interprotomer contacts and dynamics, which presumably reflect the observed changes in bending persistence length. Finally, we found that MVT decreases the density and thickness of actin filament bundles generated by VT. Altogether, our data suggest that MVT alters actin filament flexibility and tunes filament organization in the presence of VT. Both of these activities are potentially important for muscle cell function.
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    Categories: Journal Articles
  • Congenital cataract-causing mutation G129C in γC-crystallin promotes the accumulation of two distinct unfolding intermediates that form highly toxic aggregates
    [Jul 2015]

    Publication date: Available online 9 July 2015
    Source:Journal of Molecular Biology

    Author(s): Yi-Bo Xi, Xiang-Jun Chen, Wei-Jie Zhao, Yong-Bin Yan

    Cataract is a lens opacification disease prevalent worldwide. Cataract-causing mutations in crystallins generally lead to the formation of light-scattering particles in the lens. However, it remains unclear for the detailed structural and pathological mechanisms of most mutations. In this study, we showed that the G129C mutation in γC-crystallin, which is associated with autosomal dominant congenital nuclear cataract, perturbed the unfolding process by promoting the accumulation of two distinct aggregation-prone intermediates under mild denaturing conditions. The abnormally accumulated intermediates escaped from the chaperone-like function of αA-crystallin during refolding. Molecular dynamic simulations indicated that the mutation altered domain pairing geometry and allowed the penetration of extra solvent molecules into the domain binding interface, thereby weakening domain binding energy. Under mild denaturation conditions, the increased domain movements may facilitate the formation of non-native oligomers via domain-swapping, which further assembled into amyloid-like fibrils. The intermediate appeared at 1.6M guanidine hydrochloride (GdnHCl) was more compact and less aggregatory than the one populated at 0.9M GdnHCl, which was caused by the increased solvation of acidic residues in the ion-pairing network via the competitive binding of guanidinium ions. More importantly, both the amyloid-like fibrils preformed in vitro and intracellular aggresomes formed by exogenously overexpressed mutant proteins significantly inhibited cell proliferation and induced cell death. The combined data from spectroscopic, structural and cellular studies strongly suggest that both the formation of light-scattering aggregates and the toxic effects of the aggregates may contribute to the onset and development of cataract.
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    Categories: Journal Articles
  • Post-Transcriptional Regulation of Renalase Gene by miR-29 and miR-146 MicroRNAs: Implications for Cardiometabolic Disorders
    [Jul 2015]

    Publication date: Available online 9 July 2015
    Source:Journal of Molecular Biology

    Author(s): Ananthamohan Kalyani, Parshuram J. Sonawane, Abrar Ali Khan, Lakshmi Subramanian, Georg B. Ehret, Ajit S. Mullasari, Nitish R. Mahapatra

    Renalase, a recently identified oxidoreductase, is emerging as a novel regulator of cardiovascular and metabolic disease states. The mechanism of regulation of renalase gene, especially at the post-transcriptional level, is completely unknown. We set out to investigate the possible role of microRNAs in regulation of renalase gene in this study. Computational predictions using multiple algorithms coupled with systematic functional analysis revealed specific interactions of miR-29a/b/c and miR-146a/b with mouse and human renalase 3′-UTR (untranslated region) in cultured cells. Next, we estimated miR-29b and miR-146a, as well as renalase expression, in genetically hypertensive blood pressure high and genetically hypotensive blood pressure low mice. Kidney tissues from blood pressure high mice showed diminished (~1.6- to 1.8-fold) renalase mRNA/protein levels and elevated (~2.2-fold) miR-29b levels as compared to blood pressure low mice. A common single nucleotide polymorphism in human renalase 3′-UTR (C/T; rs10749571) creates a binding site for miR-146a; consistently, miR-146a down-regulated human renalase 3′-UTR/luciferase activity in case of the T allele suggesting its potential role in regulation of renalase in humans. Indeed, genome-wide association studies revealed directionally concordant association of rs10749571 with diastolic blood pressure, glucose and triglyceride levels in large human populations (n ≈58,000–96,000 subjects). This study provides evidence for post-transcriptional regulation of renalase gene by miR-29 and miR-146 and has implications for inter-individual variations on cardiometabolic traits.
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    Categories: Journal Articles