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Shi Y, Cao Q, Sun J, Hu X, Su Z, Xu Y, Zhang H, Lan L, Feng Y. The opportunistic pathogen Pseudomonas aeruginosa exploits bacterial biotin synthesis pathway to benefit its infectivity. PLoS Pathog 2023; 19:e1011110. [PMID: 36689471 PMCID: PMC9894557 DOI: 10.1371/journal.ppat.1011110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 02/02/2023] [Accepted: 01/09/2023] [Indexed: 01/24/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that predominantly causes nosocomial and community-acquired lung infections. As a member of ESKAPE pathogens, carbapenem-resistant P. aeruginosa (CRPA) compromises the limited therapeutic options, raising an urgent demand for the development of lead compounds against previously-unrecognized drug targets. Biotin is an important cofactor, of which the de novo synthesis is an attractive antimicrobial target in certain recalcitrant infections. Here we report genetic and biochemical definition of P. aeruginosa BioH (PA0502) that functions as a gatekeeper enzyme allowing the product pimeloyl-ACP to exit from fatty acid synthesis cycle and to enter the late stage of biotin synthesis pathway. In relative to Escherichia coli, P. aeruginosa physiologically requires 3-fold higher level of cytosolic biotin, which can be attributed to the occurrence of multiple biotinylated enzymes. The BioH protein enables the in vitro reconstitution of biotin synthesis. The repertoire of biotin abundance is assigned to different mouse tissues and/or organ contents, and the plasma biotin level of mouse is around 6-fold higher than that of human. Removal of bioH renders P. aeruginosa biotin auxotrophic and impairs its intra-phagosome persistence. Based on a model of CD-1 mice mimicking the human environment, lung challenge combined with systemic infection suggested that BioH is necessary for the full virulence of P. aeruginosa. As expected, the biotin synthesis inhibitor MAC13772 is capable of dampening the viability of CRPA. Notably, MAC13772 interferes the production of pyocyanin, an important virulence factor of P. aeruginosa. Our data expands our understanding of P. aeruginosa biotin synthesis relevant to bacterial infectivity. In particular, this study represents the first example of an extracellular pathogen P. aeruginosa that exploits biotin cofactor as a fitness determinant, raising the possibility of biotin synthesis as an anti-CRPA target.
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Affiliation(s)
- Yu Shi
- Department of Microbiology, and Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Qin Cao
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang, China
| | - Jingdu Sun
- Department of Microbiology, and Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiaofang Hu
- Fuzhou Medical College of Nanchang University, Fuzhou, Jiangxi, China
| | - Zhi Su
- Department of Microbiology, and Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Yongchang Xu
- Department of Microbiology, and Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Huimin Zhang
- Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Lefu Lan
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang, China
- * E-mail: (LL); (YF)
| | - Youjun Feng
- Department of Microbiology, and Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
- College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang, China
- College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
- * E-mail: (LL); (YF)
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2
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Xu Y, Yang J, Li W, Song S, Shi Y, Wu L, Sun J, Hou M, Wang J, Jia X, Zhang H, Huang M, Lu T, Gan J, Feng Y. Three enigmatic BioH isoenzymes are programmed in the early stage of mycobacterial biotin synthesis, an attractive anti-TB drug target. PLoS Pathog 2022; 18:e1010615. [PMID: 35816546 PMCID: PMC9302846 DOI: 10.1371/journal.ppat.1010615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 07/21/2022] [Accepted: 05/24/2022] [Indexed: 11/19/2022] Open
Abstract
Tuberculosis (TB) is one of the leading infectious diseases of global concern, and one quarter of the world’s population are TB carriers. Biotin metabolism appears to be an attractive anti-TB drug target. However, the first-stage of mycobacterial biotin synthesis is fragmentarily understood. Here we report that three evolutionarily-distinct BioH isoenzymes (BioH1 to BioH3) are programmed in biotin synthesis of Mycobacterium smegmatis. Expression of an individual bioH isoform is sufficient to allow the growth of an Escherichia coli ΔbioH mutant on the non-permissive condition lacking biotin. The enzymatic activity in vitro combined with biotin bioassay in vivo reveals that BioH2 and BioH3 are capable of removing methyl moiety from pimeloyl-ACP methyl ester to give pimeloyl-ACP, a cognate precursor for biotin synthesis. In particular, we determine the crystal structure of dimeric BioH3 at 2.27Å, featuring a unique lid domain. Apart from its catalytic triad, we also dissect the substrate recognition of BioH3 by pimeloyl-ACP methyl ester. The removal of triple bioH isoforms (ΔbioH1/2/3) renders M. smegmatis biotin auxotrophic. Along with the newly-identified Tam/BioC, the discovery of three unusual BioH isoforms defines an atypical ‘BioC-BioH(3)’ paradigm for the first-stage of mycobacterial biotin synthesis. This study solves a long-standing puzzle in mycobacterial nutritional immunity, providing an alternative anti-TB drug target.
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Affiliation(s)
- Yongchang Xu
- Departments of Microbiology, and General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, The People’s Republic of China
| | - Jie Yang
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry and Biophysics, School of Life Science, Fudan University, Shanghai, The People’s Republic of China
| | - Weihui Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, The People’s Republic of China
| | - Shuaijie Song
- Departments of Microbiology, and General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, The People’s Republic of China
| | - Yu Shi
- Departments of Microbiology, and General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, The People’s Republic of China
| | - Lihan Wu
- Departments of Microbiology, and General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, The People’s Republic of China
| | - Jingdu Sun
- Departments of Microbiology, and General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, The People’s Republic of China
- College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang, The People’s Republic of China
| | - Mengyun Hou
- Departments of Microbiology, and General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, The People’s Republic of China
| | - Jinzi Wang
- Guangxi Key Laboratory of Utilization of Microbial and Botanical Resources & Guangxi Key Laboratory for Polysaccharide Materials and Modifications, School of Marine Sciences and Biotechnology, Guangxi Minzu University, Nanning, Guangxi, The People’s Republic of China
| | - Xu Jia
- Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu Medical College, Chengdu, Sichuan, The People’s Republic of China
| | - Huimin Zhang
- Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Man Huang
- Departments of Microbiology, and General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, The People’s Republic of China
| | - Ting Lu
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Jianhua Gan
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry and Biophysics, School of Life Science, Fudan University, Shanghai, The People’s Republic of China
- * E-mail: (JG); (YF)
| | - Youjun Feng
- Departments of Microbiology, and General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, The People’s Republic of China
- College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang, The People’s Republic of China
- Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu Medical College, Chengdu, Sichuan, The People’s Republic of China
- * E-mail: (JG); (YF)
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3
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Sirithanakorn C, Cronan JE. Biotin, a universal and essential cofactor: Synthesis, ligation and regulation. FEMS Microbiol Rev 2021; 45:6081095. [PMID: 33428728 DOI: 10.1093/femsre/fuab003] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 01/08/2021] [Indexed: 12/22/2022] Open
Abstract
Biotin is a covalently attached enzyme cofactor required for intermediary metabolism in all three domains of life. Several important human pathogens (e.g. Mycobacterium tuberculosis) require biotin synthesis for pathogenesis. Humans lack a biotin synthetic pathway hence bacterial biotin synthesis is a prime target for new therapeutic agents. The biotin synthetic pathway is readily divided into early and late segments. Although pimelate, a seven carbon α,ω-dicarboxylic acid that contributes seven of the ten biotin carbons atoms, was long known to be a biotin precursor, its biosynthetic pathway was a mystery until the E. coli pathway was discovered in 2010. Since then, diverse bacteria encode evolutionarily distinct enzymes that replace enzymes in the E. coli pathway. Two new bacterial pimelate synthesis pathways have been elucidated. In contrast to the early pathway the late pathway, assembly of the fused rings of the cofactor, was long thought settled. However, a new enzyme that bypasses a canonical enzyme was recently discovered as well as homologs of another canonical enzyme that functions in synthesis of another protein-bound coenzyme, lipoic acid. Most bacteria tightly regulate transcription of the biotin synthetic genes in a biotin-responsive manner. The bifunctional biotin ligases which catalyze attachment of biotin to its cognate enzymes and repress biotin gene transcription are best understood regulatory system.
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Affiliation(s)
- Chaiyos Sirithanakorn
- Faculty of Medicine, King Mongkut's Institute of Technology Ladkrabang, Bangkok, Thailand.,Department of Microbiology, University of Illinois, Urbana, IL 61801, USA
| | - John E Cronan
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA.,Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
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4
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Bockman MR, Mishra N, Aldrich CC. The Biotin Biosynthetic Pathway in Mycobacterium tuberculosis is a Validated Target for the Development of Antibacterial Agents. Curr Med Chem 2020; 27:4194-4232. [PMID: 30663561 DOI: 10.2174/0929867326666190119161551] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/14/2018] [Accepted: 01/12/2019] [Indexed: 12/11/2022]
Abstract
Mycobacterium tuberculosis, responsible for Tuberculosis (TB), remains the leading cause of mortality among infectious diseases worldwide from a single infectious agent, with an estimated 1.7 million deaths in 2016. Biotin is an essential cofactor in M. tuberculosis that is required for lipid biosynthesis and gluconeogenesis. M. tuberculosis relies on de novo biotin biosynthesis to obtain this vital cofactor since it cannot scavenge sufficient biotin from a mammalian host. The biotin biosynthetic pathway in M. tuberculosis has been well studied and rigorously genetically validated providing a solid foundation for medicinal chemistry efforts. This review examines the mechanism and structure of the enzymes involved in biotin biosynthesis and ligation, summarizes the reported genetic validation studies of the pathway, and then analyzes the most promising inhibitors and natural products obtained from structure-based drug design and phenotypic screening.
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Affiliation(s)
- Matthew R Bockman
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
| | - Neeraj Mishra
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
| | - Courtney C Aldrich
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN 55455, United States
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5
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Chow J, Danso D, Ferrer M, Streit WR. The Thaumarchaeon N. gargensis carries functional bioABD genes and has a promiscuous E. coli ΔbioH-complementing esterase EstN1. Sci Rep 2018; 8:13823. [PMID: 30218044 PMCID: PMC6138646 DOI: 10.1038/s41598-018-32059-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 08/28/2018] [Indexed: 12/15/2022] Open
Abstract
Biotin is an essential cofactor required for carboxylation and decarboxylation reactions in all domains of life. While biotin biosynthesis in most Bacteria and Eukarya is well studied, the complete pathway for this vitamer in Archaea is still not known. Detailed genome searches indicated the presence of possible bio gene clusters only in Methanococcales and Thaumarchaeota. Therefore, we analysed the functionality of the predicted genes bioA, bioB, bioD and bioF in the Thaumarchaeon Nitrososphaera gargensis Ga2.9 which are essential for the later steps of biotin synthesis. In complementation tests, the gene cluster-encoded N. gargensis bioABD genes except bioF restored growth of corresponding E. coli Rosetta-gami 2 (DE3) deletion mutants. To find out how biotin biosynthesis is initiated, we searched the genome for a possible bioH analogue encoding a pimeloyl-ACP-methylester carboxylesterase. The respective amino acid sequence of the ORF estN1 showed weak conserved domain similarity to this class of enzymes (e-value 3.70e-42). Remarkably, EstN1 is a promiscuous carboxylesterase that complements E. coli ΔbioH and Mesorhizobium loti ΔbioZ mutants for growth on biotin-free minimal medium. Additional 3D-structural models support the hypothesis that EstN1 is a BioH analogue. Thus, this is the first report providing experimental evidence that Archaea carry functional bio genes.
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Affiliation(s)
- Jennifer Chow
- Microbiology and Biotechnology, University of Hamburg, 22609, Hamburg, Germany
| | - Dominik Danso
- Microbiology and Biotechnology, University of Hamburg, 22609, Hamburg, Germany
| | - Manuel Ferrer
- Institute of Catalysis, Consejo Superior de Investigaciones Científicas, 28049, Madrid, Spain
| | - Wolfgang R Streit
- Microbiology and Biotechnology, University of Hamburg, 22609, Hamburg, Germany.
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6
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Cao X, Koch T, Steffens L, Finkensieper J, Zigann R, Cronan JE, Dahl C. Lipoate-binding proteins and specific lipoate-protein ligases in microbial sulfur oxidation reveal an atpyical role for an old cofactor. eLife 2018; 7:e37439. [PMID: 30004385 PMCID: PMC6067878 DOI: 10.7554/elife.37439] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 07/12/2018] [Indexed: 01/02/2023] Open
Abstract
Many Bacteria and Archaea employ the heterodisulfide reductase (Hdr)-like sulfur oxidation pathway. The relevant genes are inevitably associated with genes encoding lipoate-binding proteins (LbpA). Here, deletion of the gene identified LbpA as an essential component of the Hdr-like sulfur-oxidizing system in the Alphaproteobacterium Hyphomicrobium denitrificans. Thus, a biological function was established for the universally conserved cofactor lipoate that is markedly different from its canonical roles in central metabolism. LbpAs likely function as sulfur-binding entities presenting substrate to different catalytic sites of the Hdr-like complex, similar to the substrate-channeling function of lipoate in carbon-metabolizing multienzyme complexes, for example pyruvate dehydrogenase. LbpAs serve a specific function in sulfur oxidation, cannot functionally replace the related GcvH protein in Bacillus subtilis and are not modified by the canonical E. coli and B. subtilis lipoyl attachment machineries. Instead, LplA-like lipoate-protein ligases encoded in or in immediate vicinity of hdr-lpbA gene clusters act specifically on these proteins.
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Affiliation(s)
- Xinyun Cao
- Department of BiochemistryUniversity of IllinoisUrbanaUnited States
| | - Tobias Koch
- Institut für Mikrobiologie and BiotechnologieRheinische Friedrich-Wilhelms-Universität BonnBonnGermany
| | - Lydia Steffens
- Institut für Mikrobiologie and BiotechnologieRheinische Friedrich-Wilhelms-Universität BonnBonnGermany
| | - Julia Finkensieper
- Institut für Mikrobiologie and BiotechnologieRheinische Friedrich-Wilhelms-Universität BonnBonnGermany
| | - Renate Zigann
- Institut für Mikrobiologie and BiotechnologieRheinische Friedrich-Wilhelms-Universität BonnBonnGermany
| | - John E Cronan
- Department of BiochemistryUniversity of IllinoisUrbanaUnited States
- Department of MicrobiologyUniversity of IllinoisUrbanaUnited States
| | - Christiane Dahl
- Institut für Mikrobiologie and BiotechnologieRheinische Friedrich-Wilhelms-Universität BonnBonnGermany
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7
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Protein moonlighting elucidates the essential human pathway catalyzing lipoic acid assembly on its cognate enzymes. Proc Natl Acad Sci U S A 2018; 115:E7063-E7072. [PMID: 29987032 DOI: 10.1073/pnas.1805862115] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The lack of attachment of lipoic acid to its cognate enzyme proteins results in devastating human metabolic disorders. These mitochondrial disorders are evident soon after birth and generally result in early death. The mutations causing specific defects in lipoyl assembly map in three genes, LIAS, LIPT1, and LIPT2 Although physiological roles have been proposed for the encoded proteins, only the LIPT1 protein had been studied at the enzyme level. LIPT1 was reported to catalyze only the second partial reaction of the classical lipoate ligase mechanism. We report that the physiologically relevant LIPT1 enzyme activity is transfer of lipoyl moieties from the H protein of the glycine cleavage system to the E2 subunits of the 2-oxoacid dehydrogenases required for respiration (e.g., pyruvate dehydrogenase) and amino acid degradation. We also report that LIPT2 encodes an octanoyl transferase that initiates lipoyl group assembly. The human pathway is now biochemically defined.
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Cao X, Hong Y, Zhu L, Hu Y, Cronan JE. Development and retention of a primordial moonlighting pathway of protein modification in the absence of selection presents a puzzle. Proc Natl Acad Sci U S A 2018; 115:647-655. [PMID: 29339506 PMCID: PMC5789953 DOI: 10.1073/pnas.1718653115] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Lipoic acid is synthesized by a remarkably atypical pathway in which the cofactor is assembled on its cognate proteins. An octanoyl moiety diverted from fatty acid synthesis is covalently attached to the acceptor protein, and sulfur insertion at carbons 6 and 8 of the octanoyl moiety form the lipoyl cofactor. Covalent attachment of this cofactor is required for function of several central metabolism enzymes, including the glycine cleavage H protein (GcvH). In Bacillus subtilis, GcvH is the sole substrate for lipoate assembly. Hence lipoic acid-requiring 2-oxoacid dehydrogenase (OADH) proteins acquire the cofactor only by transfer from lipoylated GcvH. Lipoyl transfer has been argued to be the primordial pathway of OADH lipoylation. The Escherichia coli pathway where lipoate is directly assembled on both its GcvH and OADH proteins, is proposed to have arisen later. Because roughly 3 billion years separate the divergence of these bacteria, it is surprising that E. coli GcvH functionally substitutes for the B. subtilis protein in lipoyl transfer. Known and putative GcvHs from other bacteria and eukaryotes also substitute for B. subtilis GcvH in OADH modification. Because glycine cleavage is the primary GcvH role in ancestral bacteria that lack OADH enzymes, lipoyl transfer is a "moonlighting" function: that is, development of a new function while retaining the original function. This moonlighting has been conserved in the absence of selection by some, but not all, GcvH proteins. Moreover, Aquifex aeolicus encodes five putative GcvHs, two of which have the moonlighting function, whereas others function only in glycine cleavage.
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Affiliation(s)
- Xinyun Cao
- Department of Biochemistry, University of Illinois at Urbana-Champagne, Urbana, IL 61801
| | - Yaoqin Hong
- Department of Microbiology, University of Illinois at Urbana-Champagne, Urbana, IL 61801
| | - Lei Zhu
- Department of Microbiology, University of Illinois at Urbana-Champagne, Urbana, IL 61801
| | - Yuanyuan Hu
- Department of Biochemistry, University of Illinois at Urbana-Champagne, Urbana, IL 61801
| | - John E Cronan
- Department of Biochemistry, University of Illinois at Urbana-Champagne, Urbana, IL 61801;
- Department of Microbiology, University of Illinois at Urbana-Champagne, Urbana, IL 61801
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9
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Namanja-Magliano HA, Evans GB, Harijan RK, Tyler PC, Schramm VL. Transition State Analogue Inhibitors of 5'-Deoxyadenosine/5'-Methylthioadenosine Nucleosidase from Mycobacterium tuberculosis. Biochemistry 2017; 56:5090-5098. [PMID: 28836767 DOI: 10.1021/acs.biochem.7b00576] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mycobacterium tuberculosis 5'-deoxyadenosine/5'-methylthioadenosine nucleosidase (Rv0091) catalyzes the N-riboside hydrolysis of its substrates 5'-methylthioadenosine (MTA) and 5'-deoxyadenosine (5'-dAdo). 5'-dAdo is the preferred substrate, a product of radical S-adenosylmethionine-dependent enzyme reactions. Rv0091 is characterized by a ribocation-like transition state, with low N-ribosidic bond order, an N7-protonated adenine leaving group, and an activated but weakly bonded water nucleophile. DADMe-Immucillins incorporating 5'-substituents of the substrates 5'-dAdo and MTA were synthesized and characterized as inhibitors of Rv0091. 5'-Deoxy-DADMe-Immucillin-A was the most potent among the 5'-dAdo transition state analogues with a dissociation constant of 640 pM. Among the 5'-thio substituents, hexylthio-DADMe-Immucillin-A was the best inhibitor at 87 pM. The specificity of Rv0091 for the Immucillin transition state analogues differs from those of other bacterial homologues because of an altered hydrophobic tunnel accepting the 5'-substituents. Inhibitors of Rv0091 had weak cell growth effects on M. tuberculosis or Mycobacterium smegmatis but were lethal toward Helicobacter pylori, where the 5'-methylthioadenosine nucleosidase is essential in menaquinone biosynthesis. We propose that Rv0091 plays a role in 5'-deoxyadenosine recycling but is not essential for growth in these Mycobacteria.
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Affiliation(s)
- Hilda A Namanja-Magliano
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Gary B Evans
- The Ferrier Research Institute, Victoria University of Wellington , Lower Hutt, Wellington 5040, New Zealand.,The Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland , Auckland, New Zealand
| | - Rajesh K Harijan
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Peter C Tyler
- The Ferrier Research Institute, Victoria University of Wellington , Lower Hutt, Wellington 5040, New Zealand
| | - Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine , 1300 Morris Park Avenue, Bronx, New York 10461, United States
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