title: Functional Characterization of PyrG, an Unusual Nonribosomal Peptide Synthetase Module from the Pyridomycin Biosynthetic Pathway.
abstract: Pyridomycin is an antimycobacterial cyclodepsipeptide assembled by a nonribosomal peptide synthetase/polyketide synthase hybrid system. Analysis of its cluster revealed a nonribosomal peptide synthetase (NRPS) module, PyrG, that contains two tandem adenylation domains and a PKS-type ketoreductase domain. In this study, we biochemically validated that the second A domain recognizes and activates α-keto-β-methylvaleric acid (2-KVC) as the native substrate; the first A domain was not functional but might play a structural role. The KR domain catalyzed the reduction of the 2-KVC tethered to the peptidyl carrier protein of PyrG in the presence of the MbtH family protein, PyrH. PyrG was demonstrated to recognize many amino acids. This substrate promiscuity provides the potential to generate pyridomycin analogues with various enolic acids moiety; this is important for binding InhA, a critical enzyme for cell-wall biosynthesis in Mycobacterium tuberculosis.
authors.affiliation: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Li
authors.affiliation: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
authors.forename: Nelson L
authors.initials: NL
authors.lastname: Brock
authors.affiliation: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
authors.forename: Zixin
authors.initials: Z
authors.lastname: Deng
authors.affiliation: State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China. linsj@sjtu.edu.cn.
authors.forename: Shuangjun
authors.initials: S
authors.lastname: Lin
mesh_terms: D000429:Alcohol Oxidoreductases / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D053898:Biosynthetic Pathways; D009169:Mycobacterium tuberculosis / Q000378:metabolism; D009842:Oligopeptides / Q000096:biosynthesis*; D010088:Oxidoreductases / Q000378:metabolism; D010453:Peptide Synthases / Q000737:chemistry*; D000072417:Protein Domains; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D009842:Oligopeptides; D010088:Oxidoreductases; D000429:Alcohol Oxidoreductases; C087192:polyketide synthase ketoreductase; C085257:InhA protein, Mycobacterium; D010453:Peptide Synthases; C104385:non-ribosomal peptide synthase; C458999:pyridomycin
keywords: NRP-PK hybrid; adenylation domain; biosynthesis; ketoreductase; natural products; pyridomycin