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Burley KH, Cuthbert BJ, Basu P, Newcombe J, Irimpan EM, Quechol R, Foik IP, Mobley DL, Beste DJV, Goulding CW. Structural and Molecular Dynamics of Mycobacterium tuberculosis Malic Enzyme, a Potential Anti-TB Drug Target. ACS Infect Dis 2021; 7:174-188. [PMID: 33356117 DOI: 10.1021/acsinfecdis.0c00735] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Tuberculosis (TB) is the most lethal bacterial infectious disease worldwide. It is notoriously difficult to treat, requiring a cocktail of antibiotics administered over many months. The dense, waxy outer membrane of the TB-causing agent, Mycobacterium tuberculosis (Mtb), acts as a formidable barrier against uptake of antibiotics. Subsequently, enzymes involved in maintaining the integrity of the Mtb cell wall are promising drug targets. Recently, we demonstrated that Mtb lacking malic enzyme (MEZ) has altered cell wall lipid composition and attenuated uptake by macrophages. These results suggest that MEZ contributes to lipid biosynthesis by providing reductants in the form of NAD(P)H. Here, we present the X-ray crystal structure of MEZ to 3.6 Å. We use biochemical assays to demonstrate MEZ is dimeric in solution and to evaluate the effects of pH and allosteric regulators on its kinetics and thermal stability. To assess the interactions between MEZ and its substrate malate and cofactors, Mn2+ and NAD(P)+, we ran a series of molecular dynamics (MD) simulations. First, the MD analysis corroborates our empirical observations that MEZ is unusually flexible, which persists even with the addition of substrate and cofactors. Second, the MD simulations reveal that dimeric MEZ subunits alternate between open and closed states, and that MEZ can stably bind its NAD(P)+ cofactor in multiple conformations, including an inactive, compact NAD+ form. Together the structure of MEZ and insights from its dynamics can be harnessed to inform the design of MEZ inhibitors that target Mtb and not human malic enzyme homologues.
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Affiliation(s)
| | | | - Piyali Basu
- Department of Microbial and Cellular Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom
| | - Jane Newcombe
- Department of Microbial and Cellular Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom
| | | | | | | | | | - Dany J. V. Beste
- Department of Microbial and Cellular Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7XH, United Kingdom
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Batot G, Michalska K, Ekberg G, Irimpan EM, Joachimiak G, Jedrzejczak R, Babnigg G, Hayes CS, Joachimiak A, Goulding CW. The CDI toxin of Yersinia kristensenii is a novel bacterial member of the RNase A superfamily. Nucleic Acids Res 2017; 45:5013-5025. [PMID: 28398546 PMCID: PMC5435912 DOI: 10.1093/nar/gkx230] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 03/31/2017] [Indexed: 01/01/2023] Open
Abstract
Contact-dependent growth inhibition (CDI) is an important mechanism of inter-bacterial competition found in many Gram-negative pathogens. CDI+ cells express cell-surface CdiA proteins that bind neighboring bacteria and deliver C-terminal toxin domains (CdiA-CT) to inhibit target-cell growth. CDI+ bacteria also produce CdiI immunity proteins, which specifically neutralize cognate CdiA-CT toxins to prevent self-inhibition. Here, we present the crystal structure of the CdiA-CT/CdiIYkris complex from Yersinia kristensenii ATCC 33638. CdiA-CTYkris adopts the same fold as angiogenin and other RNase A paralogs, but the toxin does not share sequence similarity with these nucleases and lacks the characteristic disulfide bonds of the superfamily. Consistent with the structural homology, CdiA-CTYkris has potent RNase activity in vitro and in vivo. Structure-guided mutagenesis reveals that His175, Arg186, Thr276 and Tyr278 contribute to CdiA-CTYkris activity, suggesting that these residues participate in substrate binding and/or catalysis. CdiIYkris binds directly over the putative active site and likely neutralizes toxicity by blocking access to RNA substrates. Significantly, CdiA-CTYkris is the first non-vertebrate protein found to possess the RNase A superfamily fold, and homologs of this toxin are associated with secretion systems in many Gram-negative and Gram-positive bacteria. These observations suggest that RNase A-like toxins are commonly deployed in inter-bacterial competition.
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Affiliation(s)
- Gaëlle Batot
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, CA 92697, USA
- These authors contributed equally to this work as first authors
| | - Karolina Michalska
- Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL 60439, USA
- Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
- These authors contributed equally to this work as first authors
| | - Greg Ekberg
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA
- These authors contributed equally to this work as first authors
| | - Ervin M. Irimpan
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, CA 92697, USA
| | - Grazyna Joachimiak
- Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Robert Jedrzejczak
- Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Gyorgy Babnigg
- Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL 60439, USA
| | - Christopher S. Hayes
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA
- Biomolecular Science and Engineering Program, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics, Argonne National Laboratory, Argonne, IL 60439, USA
- Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439, USA
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Celia W. Goulding
- Department of Molecular Biology & Biochemistry, University of California Irvine, Irvine, CA 92697, USA
- Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA 92697, USA
- To whom correspondence should be addressed. Tel: +1 949 824 0337; Fax: +1 949 824 8551
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