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  1. Article ; Online: Computational Insight into Substrate-Induced Conformational Changes in Methionyl-tRNA Synthetase of Mycobacterium Tuberculosis.

    Thakur, Shivani / Mehra, Rukmankesh

    The protein journal

    2023  Volume 42, Issue 5, Page(s) 533–546

    Abstract: Tuberculosis caused by Mycobacterium tuberculosis (M.tb) has killed millions worldwide. Antibiotic resistance leads to the ineffectiveness of the current therapies. Aminoacyl tRNA synthetase (aaRS) class of proteins involved in protein synthesis are ... ...

    Abstract Tuberculosis caused by Mycobacterium tuberculosis (M.tb) has killed millions worldwide. Antibiotic resistance leads to the ineffectiveness of the current therapies. Aminoacyl tRNA synthetase (aaRS) class of proteins involved in protein synthesis are promising bacterial targets for developing new therapies. Here, we carried out a systematic comparative study on the aaRS sequences from M.tb and human. We listed important M.tb aaRS that could be explored as potential M.tb targets alongside the detailed conformational space analysis of methionyl-tRNA synthetase (MetRS) in apo- and substrate-bound form, which is among the proposed targets. Understanding the conformational dynamics is central to the mechanistic understanding of MetRS, as the substrate binding leads to the conformational changes causing the reaction to proceed. We performed the most complete simulation study of M.tb MetRS for 6 microseconds (2 systems × 3 runs × 1 microsecond) in the apo and substrate-bound states. Interestingly, we observed differential features, showing comparatively large dynamics for the holo simulations, whereas the apo structures became slightly compact with reduced solvent exposed area. In contrast, the ligand size decreased significantly in holo structures possibly to relax ligand conformation. Our findings correlate with experimental studies, thus validating our protocol. Adenosine monophosphate moiety of the substrate exhibited quite higher fluctuations than the methionine. His21 and Lys54 were found to be the important residues forming prominent hydrogen bond and salt-bridge interactions with the ligand. The ligand-protein affinity decreased during simulations as computed by MMGBSA analysis over the last 500 ns trajectories, which indicates the conformational changes upon ligand binding. These differential features could be further explored for designing new M.tb inhibitors.
    MeSH term(s) Humans ; Methionine-tRNA Ligase/chemistry ; Methionine-tRNA Ligase/metabolism ; Mycobacterium tuberculosis/metabolism ; Ligands ; Amino Acyl-tRNA Synthetases/metabolism ; Adenosine Monophosphate/chemistry
    Chemical Substances Methionine-tRNA Ligase (EC 6.1.1.10) ; Ligands ; Amino Acyl-tRNA Synthetases (EC 6.1.1.-) ; Adenosine Monophosphate (415SHH325A)
    Language English
    Publishing date 2023-07-04
    Publishing country Netherlands
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2143071-8
    ISSN 1875-8355 ; 1572-3887
    ISSN (online) 1875-8355
    ISSN 1572-3887
    DOI 10.1007/s10930-023-10135-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Structural heterogeneity and precision of implications drawn from cryo-electron microscopy structures: SARS-CoV-2 spike-protein mutations as a test case.

    Mehra, Rukmankesh / Kepp, Kasper P

    European biophysics journal : EBJ

    2022  Volume 51, Issue 7-8, Page(s) 555–568

    Abstract: Protein structures may be used to draw functional implications at the residue level, but how sensitive are these implications to the exact structure used? Calculation of the effects of SARS-CoV-2 S-protein mutations based on experimental cryo-electron ... ...

    Abstract Protein structures may be used to draw functional implications at the residue level, but how sensitive are these implications to the exact structure used? Calculation of the effects of SARS-CoV-2 S-protein mutations based on experimental cryo-electron microscopy structures have been abundant during the pandemic. To understand the precision of such estimates, we studied three distinct methods to estimate stability changes for all possible mutations in 23 different S-protein structures (3.69 million ΔΔG values in total) and explored how random and systematic errors can be remedied by structure-averaged mutation group comparisons. We show that computational estimates have low precision, due to method and structure heterogeneity making results for single mutations uninformative. However, structure-averaged differences in mean effects for groups of substitutions can yield significant results. Illustrating this protocol, functionally important natural mutations, despite individual variations, average to a smaller stability impact compared to other possible mutations, independent of conformational state (open, closed). In summary, we document substantial issues with precision in structure-based protein modeling and recommend sensitivity tests to quantify these effects, but also suggest partial solutions to the problem in the form of structure-averaged "ensemble" estimates for groups of residues when multiple structures are available.
    MeSH term(s) Humans ; Spike Glycoprotein, Coronavirus/genetics ; Spike Glycoprotein, Coronavirus/chemistry ; Spike Glycoprotein, Coronavirus/metabolism ; Cryoelectron Microscopy ; SARS-CoV-2/genetics ; COVID-19 ; Models, Molecular ; Mutation ; Proteins/genetics
    Chemical Substances spike protein, SARS-CoV-2 ; Spike Glycoprotein, Coronavirus ; Proteins
    Language English
    Publishing date 2022-09-27
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 283671-3
    ISSN 1432-1017 ; 0175-7571
    ISSN (online) 1432-1017
    ISSN 0175-7571
    DOI 10.1007/s00249-022-01619-8
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  3. Article ; Online: Predicting virus Fitness: Towards a structure-based computational model.

    Thakur, Shivani / Planeta Kepp, Kasper / Mehra, Rukmankesh

    Journal of structural biology

    2023  Volume 215, Issue 4, Page(s) 108042

    Abstract: Predicting the impact of new emerging virus mutations is of major interest in surveillance and for understanding the evolutionary forces of the pathogens. The SARS-CoV-2 surface spike-protein (S-protein) binds to human ACE2 receptors as a critical step ... ...

    Abstract Predicting the impact of new emerging virus mutations is of major interest in surveillance and for understanding the evolutionary forces of the pathogens. The SARS-CoV-2 surface spike-protein (S-protein) binds to human ACE2 receptors as a critical step in host cell infection. At the same time, S-protein binding to human antibodies neutralizes the virus and prevents interaction with ACE2. Here we combine these two binding properties in a simple virus fitness model, using structure-based computation of all possible mutation effects averaged over 10 ACE2 complexes and 10 antibody complexes of the S-protein (∼380,000 computed mutations), and validated the approach against diverse experimental binding/escape data of ACE2 and antibodies. The ACE2-antibody selectivity change caused by mutation (i.e., the differential change in binding to ACE2 vs. immunity-inducing antibodies) is proposed to be a key metric of fitness model, enabling systematic error cancelation when evaluated. In this model, new mutations become fixated if they increase the selective binding to ACE2 relative to circulating antibodies, assuming that both are present in the host in a competitive binding situation. We use this model to categorize viral mutations that may best reach ACE2 before being captured by antibodies. Our model may aid the understanding of variant-specific vaccines and molecular mechanisms of viral evolution in the context of a human host.
    MeSH term(s) Humans ; SARS-CoV-2/genetics ; SARS-CoV-2/metabolism ; Receptors, Virus/chemistry ; Receptors, Virus/genetics ; Receptors, Virus/metabolism ; Angiotensin-Converting Enzyme 2/genetics ; Angiotensin-Converting Enzyme 2/metabolism ; Mutation ; Protein Binding
    Chemical Substances Receptors, Virus ; Angiotensin-Converting Enzyme 2 (EC 3.4.17.23)
    Language English
    Publishing date 2023-11-04
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1032718-6
    ISSN 1095-8657 ; 1047-8477
    ISSN (online) 1095-8657
    ISSN 1047-8477
    DOI 10.1016/j.jsb.2023.108042
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Structure and Mutations of SARS-CoV-2 Spike Protein: A Focused Overview.

    Mehra, Rukmankesh / Kepp, Kasper P

    ACS infectious diseases

    2021  Volume 8, Issue 1, Page(s) 29–58

    Abstract: The spike protein (S-protein) of SARS-CoV-2, the protein that enables the virus to infect human cells, is the basis for many vaccines and a hotspot of concerning virus evolution. Here, we discuss the outstanding progress in structural characterization of ...

    Abstract The spike protein (S-protein) of SARS-CoV-2, the protein that enables the virus to infect human cells, is the basis for many vaccines and a hotspot of concerning virus evolution. Here, we discuss the outstanding progress in structural characterization of the S-protein and how these structures facilitate analysis of virus function and evolution. We emphasize the differences in reported structures and that analysis of structure-function relationships is sensitive to the structure used. We show that the average residue solvent exposure in nearly complete structures is a good descriptor of open vs closed conformation states. Because of structural heterogeneity of functionally important surface-exposed residues, we recommend using averages of a group of high-quality protein structures rather than a single structure before reaching conclusions on specific structure-function relationships. To illustrate these points, we analyze some significant chemical tendencies of prominent S-protein mutations in the context of the available structures. In the discussion of new variants, we emphasize the selectivity of binding to ACE2 vs prominent antibodies rather than simply the antibody escape or ACE2 affinity separately. We note that larger chemical changes, in particular increased electrostatic charge or side-chain volume of exposed surface residues, are recurring in mutations of concern, plausibly related to adaptation to the negative surface potential of human ACE2. We also find indications that the fixated mutations of the S-protein in the main variants are less destabilizing than would be expected on average, possibly pointing toward a selection pressure on the S-protein. The richness of available structures for all of these situations provides an enormously valuable basis for future research into these structure-function relationships.
    MeSH term(s) COVID-19 ; Humans ; Mutation ; Protein Binding ; SARS-CoV-2 ; Spike Glycoprotein, Coronavirus/genetics ; Spike Glycoprotein, Coronavirus/metabolism
    Chemical Substances Spike Glycoprotein, Coronavirus ; spike protein, SARS-CoV-2
    Language English
    Publishing date 2021-12-02
    Publishing country United States
    Document type Journal Article
    ISSN 2373-8227
    ISSN (online) 2373-8227
    DOI 10.1021/acsinfecdis.1c00433
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Stability and expression of SARS-CoV-2 spike-protein mutations.

    Bæk, Kristoffer T / Mehra, Rukmankesh / Kepp, Kasper P

    Molecular and cellular biochemistry

    2022  Volume 478, Issue 6, Page(s) 1269–1280

    Abstract: Protein fold stability likely plays a role in SARS-CoV-2 S-protein evolution, together with ACE2 binding and antibody evasion. While few thermodynamic stability data are available for S-protein mutants, many systematic experimental data exist for their ... ...

    Abstract Protein fold stability likely plays a role in SARS-CoV-2 S-protein evolution, together with ACE2 binding and antibody evasion. While few thermodynamic stability data are available for S-protein mutants, many systematic experimental data exist for their expression. In this paper, we explore whether such expression levels relate to the thermodynamic stability of the mutants. We studied mutation-induced SARS-CoV-2 S-protein fold stability, as computed by three very distinct methods and eight different protein structures to account for method- and structure-dependencies. For all methods and structures used (24 comparisons), computed stability changes correlate significantly (99% confidence level) with experimental yeast expression from the literature, such that higher expression is associated with relatively higher fold stability. Also significant, albeit weaker, correlations were seen between stability and ACE2 binding effects. The effect of thermodynamic fold stability may be direct or a correlate of amino acid or site properties, notably the solvent exposure of the site. Correlation between computed stability and experimental expression and ACE2 binding suggests that functional properties of the SARS-CoV-2 S-protein mutant space are largely determined by a few simple features, due to underlying correlations. Our study lends promise to the development of computational tools that may ideally aid in understanding and predicting SARS-CoV-2 S-protein evolution.
    MeSH term(s) Humans ; SARS-CoV-2/genetics ; COVID-19/genetics ; Binding Sites ; Protein Binding ; Angiotensin-Converting Enzyme 2/genetics ; Angiotensin-Converting Enzyme 2/metabolism ; Spike Glycoprotein, Coronavirus/genetics ; Spike Glycoprotein, Coronavirus/chemistry ; Mutation
    Chemical Substances Angiotensin-Converting Enzyme 2 (EC 3.4.17.23) ; spike protein, SARS-CoV-2 ; Spike Glycoprotein, Coronavirus
    Language English
    Publishing date 2022-10-27
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 184833-1
    ISSN 1573-4919 ; 0300-8177
    ISSN (online) 1573-4919
    ISSN 0300-8177
    DOI 10.1007/s11010-022-04588-w
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  6. Article ; Online: Identification of Structural Calcium Binding Sites in Membrane-Bound Presenilin 1 and 2.

    Mehra, Rukmankesh / Kepp, Kasper P

    The journal of physical chemistry. B

    2020  Volume 124, Issue 23, Page(s) 4697–4711

    Abstract: Variants of presenilin (PS1 and PS2) are the main genetic risk factors of familial Alzheimer's disease and thus central to the disease etiology. Although mostly studied as catalytic units of γ-secretase controlling Aβ production, presenilins also affect ... ...

    Abstract Variants of presenilin (PS1 and PS2) are the main genetic risk factors of familial Alzheimer's disease and thus central to the disease etiology. Although mostly studied as catalytic units of γ-secretase controlling Aβ production, presenilins also affect calcium levels, which are disturbed in Alzheimer's disease. We investigated the interaction of calcium with both PS1 and PS2 using all-atom molecular dynamics (MD) simulations in realistic membrane models, with the specific aim to identify any Ca
    MeSH term(s) Alzheimer Disease/genetics ; Amyloid Precursor Protein Secretases/metabolism ; Binding Sites ; Calcium ; Humans ; Presenilin-1/genetics
    Chemical Substances Presenilin-1 ; Amyloid Precursor Protein Secretases (EC 3.4.-) ; Calcium (SY7Q814VUP)
    Language English
    Publishing date 2020-06-02
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1520-5207
    ISSN (online) 1520-5207
    DOI 10.1021/acs.jpcb.0c01712
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  7. Article ; Online: Computational prediction and molecular mechanism of γ-secretase modulators.

    Mehra, Rukmankesh / Kepp, Kasper P

    European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences

    2020  Volume 157, Page(s) 105626

    Abstract: Selective control over Aβ production via γ-secretase modulators (GSM) is a promising strategy for treating Alzheimer's disease, yet the specific binding sites and mechanism of action of GSMs remain unknown. Using the recent cryo-electron microscopy ... ...

    Abstract Selective control over Aβ production via γ-secretase modulators (GSM) is a promising strategy for treating Alzheimer's disease, yet the specific binding sites and mechanism of action of GSMs remain unknown. Using the recent cryo-electron microscopy structures of substrate-bound γ-secretase we used two distinct methods to identify four potential binding sites for pyridopyrazine-1,6-dione GSMs. We demonstrate binding to site 4 formed between PS1-TM2, PS1-TM5 and the APP-C83-TM, with experimental activity data correlating significantly (95% confidence) with our computed binding-affinities for this site. Charged protonated GSMs may display higher affinities because of π-cation interaction with the polar residue Tyr115 of PS1-NTF. Surprisingly, the pIC
    MeSH term(s) Alzheimer Disease ; Amyloid Precursor Protein Secretases/metabolism ; Binding Sites ; Cryoelectron Microscopy ; Humans ; Protein Domains
    Chemical Substances Amyloid Precursor Protein Secretases (EC 3.4.-)
    Language English
    Publishing date 2020-10-25
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 1154366-8
    ISSN 1879-0720 ; 0928-0987
    ISSN (online) 1879-0720
    ISSN 0928-0987
    DOI 10.1016/j.ejps.2020.105626
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  8. Article ; Online: Modelling SARS-CoV-2 spike-protein mutation effects on ACE2 binding.

    Thakur, Shivani / Verma, Rajaneesh Kumar / Kepp, Kasper Planeta / Mehra, Rukmankesh

    Journal of molecular graphics & modelling

    2022  Volume 119, Page(s) 108379

    Abstract: The binding affinity of the SARS-CoV-2 spike (S)-protein to the human membrane protein ACE2 is critical for virus function. Computational structure-based screening of new S-protein mutations for ACE2 binding lends promise to rationalize virus function ... ...

    Abstract The binding affinity of the SARS-CoV-2 spike (S)-protein to the human membrane protein ACE2 is critical for virus function. Computational structure-based screening of new S-protein mutations for ACE2 binding lends promise to rationalize virus function directly from protein structure and ideally aid early detection of potentially concerning variants. We used a computational protocol based on cryo-electron microscopy structures of the S-protein to estimate the change in ACE2-affinity due to S-protein mutation (ΔΔG
    MeSH term(s) Humans ; Angiotensin-Converting Enzyme 2/genetics ; COVID-19/genetics ; Cryoelectron Microscopy ; SARS-CoV-2/genetics ; Spike Glycoprotein, Coronavirus/genetics ; Hydrolases ; Mutation ; Protein Binding
    Chemical Substances spike protein, SARS-CoV-2 ; Angiotensin-Converting Enzyme 2 (EC 3.4.17.23) ; Spike Glycoprotein, Coronavirus ; Hydrolases (EC 3.-)
    Language English
    Publishing date 2022-11-24
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1396450-1
    ISSN 1873-4243 ; 1093-3263
    ISSN (online) 1873-4243
    ISSN 1093-3263
    DOI 10.1016/j.jmgm.2022.108379
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  9. Article ; Online: Computational fitness estimates of SARS-CoV-2 mutations affecting spike protein binding to antibodies and ACE2

    Thakur, Shivani / Kepp, Kasper Planeta / Mehra, Rukmankesh

    bioRxiv

    Abstract: Predicting the impact of new emerging virus mutations is of major interest in surveillance and for understanding the evolutionary forces of the pathogen. The SARS-CoV-2 surface spike-protein (S-protein) binds to human ACE2 receptors as a critical step in ...

    Abstract Predicting the impact of new emerging virus mutations is of major interest in surveillance and for understanding the evolutionary forces of the pathogen. The SARS-CoV-2 surface spike-protein (S-protein) binds to human ACE2 receptors as a critical step in host cell infection. At the same time, S-protein binding to human antibodies neutralizes the virus and prevents interaction with ACE2. Here we combine these two binding properties in a simple fitness model, using structure-based computation of all possible mutation effects averaged over 10 ACE2 complexes and 10 antibody complexes of the S-protein. The ACE2-antibody selectivity change caused by mutation (i.e., the change binding to ACE2 minus the change in binding to immunity-inducing antibodies) is proposed to be a key metric of virus fitness, which furthermore enables substantial systematic error cancelation when evaluated. In this model, new mutations become fixated if they increase the selective binding to ACE2 relative to circulating antibodies, assuming that both are present in the host in a competitive binding situation. We use this model to categorize viral mutations that may best reach ACE2 before being captured by antibodies. Our model may aid the understanding of variant-specific vaccines and molecular mechanisms of viral evolution in the context of a human host.
    Keywords covid19
    Language English
    Publishing date 2023-05-02
    Publisher Cold Spring Harbor Laboratory
    Document type Article ; Online
    DOI 10.1101/2023.05.01.538902
    Database COVID19

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  10. Article ; Online: Cell size effects in the molecular dynamics of the intrinsically disordered Aβ peptide.

    Mehra, Rukmankesh / Kepp, Kasper P

    The Journal of chemical physics

    2019  Volume 151, Issue 8, Page(s) 85101

    Abstract: Periodic molecular dynamics simulations of proteins may suffer from image interactions. Similarly, the hydrophobic effect required to keep a protein folded may not be enforced by small simulation cells. Accordingly, errors may arise both from the water ... ...

    Abstract Periodic molecular dynamics simulations of proteins may suffer from image interactions. Similarly, the hydrophobic effect required to keep a protein folded may not be enforced by small simulation cells. Accordingly, errors may arise both from the water concentration per se and the image interactions. Intrinsically disordered proteins are particularly sensitive, providing a worst-case estimate of the errors. Following this reasoning, we studied Aβ
    MeSH term(s) Amyloid beta-Peptides/chemistry ; Cell Size ; Humans ; Hydrophobic and Hydrophilic Interactions ; Intrinsically Disordered Proteins/chemistry ; Molecular Dynamics Simulation ; Protein Conformation
    Chemical Substances Amyloid beta-Peptides ; Intrinsically Disordered Proteins
    Language English
    Publishing date 2019-09-13
    Publishing country United States
    Document type Journal Article
    ZDB-ID 3113-6
    ISSN 1089-7690 ; 0021-9606
    ISSN (online) 1089-7690
    ISSN 0021-9606
    DOI 10.1063/1.5115085
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