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Jones BS, Pareek V, Hu DD, Weaver SD, Syska C, Galfano G, Champion MM, Champion PA. N - acetyl-transferases required for iron uptake and aminoglycoside resistance promote virulence lipid production in M. marinum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.05.602253. [PMID: 39005365 PMCID: PMC11245092 DOI: 10.1101/2024.07.05.602253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
Phagosomal lysis is a key aspect of mycobacterial infection of host macrophages. Acetylation is a protein modification mediated enzymatically by N-acetyltransferases (NATs) that impacts bacterial pathogenesis and physiology. To identify NATs required for lytic activity, we leveraged Mycobacterium marinum, a nontubercular pathogen and an established model for M. tuberculosis. M. marinum hemolysis is a proxy for phagolytic activity. We generated M. marinum strains with deletions in conserved NAT genes and screened for hemolytic activity. Several conserved lysine acetyltransferases (KATs) contributed to hemolysis. Hemolysis is mediated by the ESX-1 secretion system and by phthiocerol dimycocerosate (PDIM), a virulence lipid. For several strains, the hemolytic activity was restored by the addition of second copy of the ESX-1 locus. Using thin-layer chromatography (TLC), we found a single NAT required for PDIM and phenolic glycolipid (PGL) production. MbtK is a conserved KAT required for mycobactin siderophore synthesis and virulence. Mycobactin J exogenously complemented PDIM/PGL production in the Δ mbtK strain. The Δ mbtK M. marinum strain was attenuated in macrophage and Galleria mellonella infection models. Constitutive expression of either eis or papA5, which encode a KAT required for aminoglycoside resistance and a PDIM/PGL biosynthetic enzyme, rescued PDIM/PGL production and virulence of the Δ mbtK strain. Eis N-terminally acetylated PapA5 in vitro , supporting a mechanism for restored lipid production. Overall, our study establishes connections between the MbtK and Eis NATs, and between iron uptake and PDIM and PGL synthesis in M. marinum . Our findings underscore the multifunctional nature of mycobacterial NATs and their connection to key virulence pathways. Significance Statement Acetylation is a modification of protein N-termini, lysine residues, antibiotics and lipids. Many of the enzymes that promote acetylation belong to the GNAT family of proteins. M. marinum is a well-established as a model to understand how M. tuberculosis causes tuberculosis. In this study we sought to identify conserved GNAT proteins required for early stages of mycobacterial infection. Using M. marinum, we determined that several GNAT proteins are required for the lytic activity of M. marinum. We uncovered previously unknown connections between acetyl-transferases required for iron uptake and antimicrobial resistance, and the production of the unique mycobacterial lipids, PDIM and PGLOur data support that acetyl-transferases from the GNAT family are interconnected, and have activities beyond those previously reported.
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Guzmán L, Cambier CJ, Cheng TY, Naqvi KF, Shiloh MU, Moody DB, Bertozzi CR. Bioorthogonal Metabolic Labeling of the Virulence Factor Phenolic Glycolipid in Mycobacteria. ACS Chem Biol 2024; 19:707-717. [PMID: 38442242 PMCID: PMC10949201 DOI: 10.1021/acschembio.3c00724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 02/15/2024] [Accepted: 02/21/2024] [Indexed: 03/07/2024]
Abstract
Surface lipids on pathogenic mycobacteria modulate infection outcomes by regulating host immune responses. Phenolic glycolipid (PGL) is a host-modulating surface lipid that varies among clinical Mycobacterium tuberculosis strains. PGL is also found in Mycobacterium marinum, where it promotes infection of zebrafish through effects on the innate immune system. Given the important role this lipid plays in the host-pathogen relationship, tools for profiling its abundance, spatial distribution, and dynamics are needed. Here, we report a strategy for imaging PGL in live mycobacteria using bioorthogonal metabolic labeling. We functionalized the PGL precursor p-hydroxybenzoic acid (pHB) with an azide group (3-azido pHB). When fed to mycobacteria, 3-azido pHB was incorporated into the cell surface, which could then be visualized via the bioorthogonal conjugation of a fluorescent probe. We confirmed that 3-azido pHB incorporates into PGL using mass spectrometry methods and demonstrated selectivity for PGL-producing M. marinum and M. tuberculosis strains. Finally, we applied this metabolic labeling strategy to study the dynamics of PGL within the mycobacterial membrane. This new tool enables visualization of PGL that may facilitate studies of mycobacterial pathogenesis.
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Affiliation(s)
- Lindsay
E. Guzmán
- Stanford
Sarafan ChEM-H, Stanford University, Stanford, California 94305, United States
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - C. J. Cambier
- Stanford
Sarafan ChEM-H, Stanford University, Stanford, California 94305, United States
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Tan-Yun Cheng
- Brigham
and Women’s Hospital, Division of Rheumatology, Inflammation
and Immunity, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Kubra F. Naqvi
- Department
of Internal Medicine, University of Texas
Southwestern Medical Center, Dallas, Texas 75390, United States
- Department
of Microbiology, University of Texas Southwestern
Medical Center, Dallas, Texas 75390, United States
| | - Michael U. Shiloh
- Department
of Internal Medicine, University of Texas
Southwestern Medical Center, Dallas, Texas 75390, United States
- Department
of Microbiology, University of Texas Southwestern
Medical Center, Dallas, Texas 75390, United States
| | - D. Branch Moody
- Brigham
and Women’s Hospital, Division of Rheumatology, Inflammation
and Immunity, Harvard Medical School, Boston, Massachusetts 02115, United States
| | - Carolyn R. Bertozzi
- Stanford
Sarafan ChEM-H, Stanford University, Stanford, California 94305, United States
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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3
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Zhao J, Wei W, Yan H, Zhou Y, Li Z, Chen Y, Zhang C, Zeng J, Chen T, Zhou L. Assessing capreomycin resistance on tlyA deficient and point mutation (G695A) Mycobacterium tuberculosis strains using multi-omics analysis. Int J Med Microbiol 2019; 309:151323. [PMID: 31279617 DOI: 10.1016/j.ijmm.2019.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/26/2019] [Accepted: 06/22/2019] [Indexed: 10/26/2022] Open
Abstract
Capreomycin (CAP), a cyclic peptide antibiotic, is considered to be an ideal second-line drug for tuberculosis (TB). However, in the past few years, the emergence of more CAP-resistant (CAPr) TB patients has limited its use. Although it has been reported that CAP resistance to Mycobacterium tuberculosis (Mtb) is associated with rrs or tlyA mutation, the exact mechanism of CAPr Mtb strains, especially the mechanism associated with tlyA deficient or mutation, is not fully understood. Herein, we utilized a multi-omics (genome, proteome, and metabolome) approach to assess CAP resistance on tlyA deficient CAPr Mtb strains (CAPr1) and tlyA point mutation CAPr Mtb strains (CAPr2) that we established for the first time in vitro to investigate the CAP-resistant mechanism. Our results showed that the CAPr1 strains (> 40 μg/ml) was more resistant to CAP than the CAPr2 strains (G695A, 10 μg/ml). Furthermore, multi-omics analysis indicated that the CAPr1 strains exhibited greater drug tolerance than the CAPr2 strains may be associated with the weakening of S-adenosyl-L-methionine-dependent methyltransferase (AdoMet-MT) activity and abnormal membrane lipid metabolism such as suppression of fatty acid metabolism, promotion of glycolipid phospholipid and glycerolipid metabolism. As a result, these studies reveal a new mechanism for CAP resistance to tlyA deficient or mutation Mtb strains, and may be helpful in developing new therapeutic approaches to prevent Mtb resistance to CAP.
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Affiliation(s)
- Jiao Zhao
- Jinan University, Guangzhou 510632, China
| | - Wenjing Wei
- Center for Tuberculosis Control of Guangdong Province, Key Laboratory of Translational Medicine of Guangdong, Guangzhou 510630, China
| | - Huimin Yan
- Dongguang Key Laboratory of Medical Bioactive Molecular Development and Translational Research, Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Guangdong Medical University, Dongguan, Guangdong, 523808, China
| | - Ying Zhou
- School of Stomatology and Medicine, Foshan University, Foshan, Guangdong, 528000, China
| | - Zhenyan Li
- The First Affiliated Hospital, Jinan University, Guangzhou 510630, China
| | - Yanmei Chen
- Center for Tuberculosis Control of Guangdong Province, Key Laboratory of Translational Medicine of Guangdong, Guangzhou 510630, China
| | - Chenchen Zhang
- Center for Tuberculosis Control of Guangdong Province, Key Laboratory of Translational Medicine of Guangdong, Guangzhou 510630, China
| | - Jincheng Zeng
- Dongguang Key Laboratory of Medical Bioactive Molecular Development and Translational Research, Guangdong Provincial Key Laboratory of Medical Molecular Diagnostics, Guangdong Medical University, Dongguan, Guangdong, 523808, China.
| | - Tao Chen
- Center for Tuberculosis Control of Guangdong Province, Key Laboratory of Translational Medicine of Guangdong, Guangzhou 510630, China; South China Institute of Biomedicine, Guangzhou 510530, China.
| | - Lin Zhou
- Center for Tuberculosis Control of Guangdong Province, Key Laboratory of Translational Medicine of Guangdong, Guangzhou 510630, China; Jinan University, Guangzhou 510632, China.
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4
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Timofeeva LM, Balakaeva IV, Lileev AS, Simonova YA, Lyashchenko AK. General trends in concentration and temperature behavior of equivalent conductance of N,N-diallylammonium polymers aqueous solutions: Effect of counterion nature and amine structure. POLYMER SCIENCE SERIES C 2017. [DOI: 10.1134/s1811238217010131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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Barnes DD, Lundahl MLE, Lavelle EC, Scanlan EM. The Emergence of Phenolic Glycans as Virulence Factors in Mycobacterium tuberculosis. ACS Chem Biol 2017; 12:1969-1979. [PMID: 28692249 DOI: 10.1021/acschembio.7b00394] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Tuberculosis is the leading infectious cause of mortality worldwide. The global epidemic, caused by Mycobacterium tuberculosis, has prompted renewed interest in the development of novel vaccines for disease prevention and control. The cell envelope of M. tuberculosis is decorated with an assortment of glycan structures, including glycolipids, that are involved in disease pathogenesis. Phenolic glycolipids and the structurally related para-hydroxybenzoic acid derivatives display potent immunomodulatory activities and have particular relevance for both understanding the interaction of the bacterium with the host immune system and also in the design of new vaccine and therapeutic candidates. Interest in glycobiology has grown exponentially over the past decade, with advancements paving the way for effective carbohydrate based vaccines. This review highlights recent advances in our understanding of phenolic glycans, including their biosynthesis and role as virulence factors in M. tuberculosis. Recent chemical synthesis approaches and biochemical analysis of synthetic glycans and their conjugates have led to fundamental insights into their roles in host-pathogen interactions. The applications of these synthetic glycans as potential vaccine candidates are discussed.
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Affiliation(s)
- Danielle D. Barnes
- School of Chemistry
and Trinity Biomedical Sciences Institute, Trinity College, Pearse
St., Dublin 2, Ireland
| | - Mimmi L. E. Lundahl
- School of Chemistry
and Trinity Biomedical Sciences Institute, Trinity College, Pearse
St., Dublin 2, Ireland
- Adjuvant Research Group, School of Biochemistry and Immunology, Trinity
Biomedical Sciences Institute, Trinity College Dublin, D02 R590, Dublin 2, Ireland
| | - Ed C. Lavelle
- Adjuvant Research Group, School of Biochemistry and Immunology, Trinity
Biomedical Sciences Institute, Trinity College Dublin, D02 R590, Dublin 2, Ireland
| | - Eoin M. Scanlan
- School of Chemistry
and Trinity Biomedical Sciences Institute, Trinity College, Pearse
St., Dublin 2, Ireland
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6
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012. MASS SPECTROMETRY REVIEWS 2017; 36:255-422. [PMID: 26270629 DOI: 10.1002/mas.21471] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 01/15/2015] [Indexed: 06/04/2023]
Abstract
This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.
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Affiliation(s)
- David J Harvey
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford, OX1 3QU, UK
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7
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F420H2 Is Required for Phthiocerol Dimycocerosate Synthesis in Mycobacteria. J Bacteriol 2016; 198:2020-8. [PMID: 27185825 DOI: 10.1128/jb.01035-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 05/06/2016] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED Phthiocerol dimycocerosates (PDIM) are a group of cell surface-associated apolar lipids of Mycobacterium tuberculosis and closely related mycobacteria, such as Mycobacterium bovis and Mycobacterium leprae A characteristic methoxy group of these lipids is generated from the methylation of a hydroxyl group of the direct precursors, the phthiotriols. The precursors arise from the reduction of phthiodiolones, the keto intermediates, by a ketoreductase. The putative phthiodiolone ketoreductase (PKR) is encoded by Rv2951c in M. tuberculosis and BCG_2972c in M. bovis BCG, and these open reading frames (ORFs) encode identical amino acid sequences. We investigated the cofactor requirement of the BCG_2972c protein. A comparative analysis based on the crystallographic structures of similar enzymes identified structural elements for binding of coenzyme F420 and hydrophobic phthiodiolones in PKR. Coenzyme F420 is a deazaflavin coenzyme that serves several key functions in pathogenic and nonpathogenic mycobacteria. We found that an M. bovis BCG mutant lacking F420-dependent glucose-6-phosphate dehydrogenase (Fgd), which generates F420H2 (glucose-6-phosphate + F420 → 6-phosphogluconate + F420H2), was devoid of phthiocerols and accumulated phthiodiolones. When the mutant was provided with F420H2, a broken-cell slurry of the mutant converted accumulated phthiodiolones to phthiocerols; F420H2 was generated in situ from F420 and glucose-6-phosphate by the action of Fgd. Thus, the reaction mixture was competent in reducing phthiodiolones to phthiotriols (phthiodiolones + F420H2 → phthiotriols + F420), which were then methylated to phthiocerols. These results established the mycobacterial phthiodiolone ketoreductase as an F420H2-dependent enzyme (fPKR). A phylogenetic analysis of close homologs of fPKR revealed potential F420-dependent lipid-modifying enzymes in a broad range of mycobacteria. IMPORTANCE Mycobacterium tuberculosis is the causative agent of tuberculosis, and phthiocerol dimycocerosates (PDIM) protect this pathogen from the early innate immune response of an infected host. Thus, the PDIM synthesis system is a potential target for the development of effective treatments for tuberculosis. The current study shows that a PDIM synthesis enzyme is dependent on the coenzyme F420 F420 is universally present in mycobacteria and absent in humans. This finding expands the number of experimentally validated F420-dependent enzymes in M. tuberculosis to six, each of which helps the pathogen to evade killing by the host immune system, and one of which activates an antituberculosis drug, PA-824. This work also has relevance to leprosy, since similar waxy lipids are found in Mycobacterium leprae.
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8
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Mohandas P, Budell WC, Mueller E, Au A, Bythrow GV, Quadri LEN. Pleiotropic consequences of gene knockouts in the phthiocerol dimycocerosate and phenolic glycolipid biosynthetic gene cluster of the opportunistic human pathogen Mycobacterium marinum. FEMS Microbiol Lett 2016; 363:fnw016. [PMID: 26818253 DOI: 10.1093/femsle/fnw016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/23/2016] [Indexed: 11/14/2022] Open
Abstract
Phthiocerol dimycocerosates (PDIMs) and phenolic glycolipids (PGLs) contribute to the pathogenicity of several mycobacteria. Biosynthesis of these virulence factors requires polyketide synthases and other enzymes that represent potential targets for the development of adjuvant antivirulence drugs. We used six isogenic Mycobacterium marinum mutants, each with a different gene knockout in the PDIM/PGL biosynthetic pathway, to probe the pleiotropy of mutations leading to PDIM(-) PGL(-), PDIM(+) PGL(-) or PDIM(-) PGL(+) phenotypes. We evaluated the M. marinum mutants for changes in antibiotic susceptibility, cell envelope permeability, biofilm formation, surface properties, sliding motility and virulence in an amoeba model. The analysis also permitted us to begin exploring the hypothesis that different gene knockouts rendering the same PDIM and/or PGL deficiency phenotypes lead to M. marinum mutants with equivalent pleiotropic profiles. Overall, the results of our study revealed a complex picture of pleiotropic patterns emerging from different gene knockouts, uncovered unexpected phenotypic inequalities between mutants, and provided new insight into the phenotypic consequences of gene knockouts in the PDIM/PGL biosynthetic pathway.
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Affiliation(s)
- Poornima Mohandas
- Biology Department, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA Biology Program, Graduate Center, City University of New York, NY 10016, USA
| | - William C Budell
- Biology Department, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA Biology Program, Graduate Center, City University of New York, NY 10016, USA
| | - Emily Mueller
- Biology Department, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA
| | - Andrew Au
- Biology Department, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA
| | - Glennon V Bythrow
- Biology Department, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA Biology Program, Graduate Center, City University of New York, NY 10016, USA
| | - Luis E N Quadri
- Biology Department, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA Biology Program, Graduate Center, City University of New York, NY 10016, USA
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9
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Touchette MH, Bommineni GR, Delle Bovi RJ, Gadbery JE, Nicora CD, Shukla AK, Kyle JE, Metz TO, Martin DW, Sampson NS, Miller WT, Tonge PJ, Seeliger JC. Diacyltransferase Activity and Chain Length Specificity of Mycobacterium tuberculosis PapA5 in the Synthesis of Alkyl β-Diol Lipids. Biochemistry 2015; 54:5457-68. [PMID: 26271001 DOI: 10.1021/acs.biochem.5b00455] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although they are classified as Gram-positive bacteria, Corynebacterineae possess an asymmetric outer membrane that imparts structural and thereby physiological similarity to more distantly related Gram-negative bacteria. Like lipopolysaccharide in Gram-negative bacteria, lipids in the outer membrane of Corynebacterineae have been associated with the virulence of pathogenic species such as Mycobacterium tuberculosis (Mtb). For example, Mtb strains that lack long, branched-chain alkyl esters known as dimycocerosates (DIMs) are significantly attenuated in model infections. The resultant interest in the biosynthetic pathway of these unusual virulence factors has led to the elucidation of many of the steps leading to the final esterification of the alkyl β-diol, phthiocerol, with branched-chain fatty acids known as mycocerosates. PapA5 is an acyltransferase implicated in these final reactions. Here, we show that PapA5 is indeed the terminal enzyme in DIM biosynthesis by demonstrating its dual esterification activity and chain-length preference using synthetic alkyl β-diol substrate analogues. By applying these analogues to a series of PapA5 mutants, we also revise a model for the substrate binding within PapA5. Finally, we demonstrate that the Mtb Ser/Thr kinases PknB and PknE modify PapA5 on three overlapping Thr residues and that a fourth Thr is unique to PknE phosphorylation. These results clarify the DIM biosynthetic pathway and indicate post-translational modifications that warrant further elucidation for their roles in the regulation of DIM biosynthesis.
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Affiliation(s)
| | | | | | | | - Carrie D Nicora
- Biological Sciences Division, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Anil K Shukla
- Biological Sciences Division, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Jennifer E Kyle
- Biological Sciences Division, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Thomas O Metz
- Biological Sciences Division, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
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10
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Timofeeva LM, Kleshcheva NA, Shleeva MO, Filatova MP, Simonova YA, Ermakov YA, Kaprelyants AS. Nonquaternary poly(diallylammonium) polymers with different amine structure and their biocidal effect on Mycobacterium tuberculosis and Mycobacterium smegmatis. Appl Microbiol Biotechnol 2015; 99:2557-71. [DOI: 10.1007/s00253-014-6331-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 12/12/2014] [Accepted: 12/14/2014] [Indexed: 01/12/2023]
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11
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Biosynthesis of cell envelope-associated phenolic glycolipids in Mycobacterium marinum. J Bacteriol 2015; 197:1040-50. [PMID: 25561717 DOI: 10.1128/jb.02546-14] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phenolic glycolipids (PGLs) are polyketide synthase-derived glycolipids unique to pathogenic mycobacteria. PGLs are found in several clinically relevant species, including various Mycobacterium tuberculosis strains, Mycobacterium leprae, and several nontuberculous mycobacterial pathogens, such as M. marinum. Multiple lines of investigation implicate PGLs in virulence, thus underscoring the relevance of a deep understanding of PGL biosynthesis. We report mutational and biochemical studies that interrogate the mechanism by which PGL biosynthetic intermediates (p-hydroxyphenylalkanoates) synthesized by the iterative polyketide synthase Pks15/1 are transferred to the noniterative polyketide synthase PpsA for acyl chain extension in M. marinum. Our findings support a model in which the transfer of the intermediates is dependent on a p-hydroxyphenylalkanoyl-AMP ligase (FadD29) acting as an intermediary between the iterative and the noniterative synthase systems. Our results also establish the p-hydroxyphenylalkanoate extension ability of PpsA, the first-acting enzyme of a multisubunit noniterative polyketide synthase system. Notably, this noniterative system is also loaded with fatty acids by a specific fatty acyl-AMP ligase (FadD26) for biosynthesis of phthiocerol dimycocerosates (PDIMs), which are nonglycosylated lipids structurally related to PGLs. To our knowledge, the partially overlapping PGL and PDIM biosynthetic pathways provide the first example of two distinct, pathway-dedicated acyl-AMP ligases loading the same type I polyketide synthase system with two alternate starter units to produce two structurally different families of metabolites. The studies reported here advance our understanding of the biosynthesis of an important group of mycobacterial glycolipids.
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The Polyketide Synthase Pks13 Catalyzes a Novel Mechanism of Lipid Transfer in Mycobacteria. ACTA ACUST UNITED AC 2014; 21:1660-9. [DOI: 10.1016/j.chembiol.2014.10.011] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 10/10/2014] [Accepted: 10/15/2014] [Indexed: 11/19/2022]
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13
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Quadri LEN. Biosynthesis of mycobacterial lipids by polyketide synthases and beyond. Crit Rev Biochem Mol Biol 2014; 49:179-211. [DOI: 10.3109/10409238.2014.896859] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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14
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Abstract
Long-chain-length hydrophobic acyl residues play a vital role in a multitude of essential biological structures and processes. They build the inner hydrophobic layers of biological membranes, are converted to intracellular storage compounds, and are used to modify protein properties or function as membrane anchors, to name only a few functions. Acyl thioesters are transferred by acyltransferases or transacylases to a variety of different substrates or are polymerized to lipophilic storage compounds. Lipases represent another important enzyme class dealing with fatty acyl chains; however, they cannot be regarded as acyltransferases in the strict sense. This review provides a detailed survey of the wide spectrum of bacterial acyltransferases and compares different enzyme families in regard to their catalytic mechanisms. On the basis of their studied or assumed mechanisms, most of the acyl-transferring enzymes can be divided into two groups. The majority of enzymes discussed in this review employ a conserved acyltransferase motif with an invariant histidine residue, followed by an acidic amino acid residue, and their catalytic mechanism is characterized by a noncovalent transition state. In contrast to that, lipases rely on completely different mechanism which employs a catalytic triad and functions via the formation of covalent intermediates. This is, for example, similar to the mechanism which has been suggested for polyester synthases. Consequently, although the presented enzyme types neither share homology nor have a common three-dimensional structure, and although they deal with greatly varying molecule structures, this variety is not reflected in their mechanisms, all of which rely on a catalytically active histidine residue.
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Affiliation(s)
- Annika Röttig
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, Münster, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität, Münster, Germany
- Environmental Sciences Department, King Abdulaziz University, Jeddah, Saudi Arabia
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