title: Biosynthesis of cell envelope-associated phenolic glycolipids in Mycobacterium marinum.
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.
authors.affiliation: Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, USA.
authors.forename: Olivia
authors.initials: O
authors.lastname: Vergnolle
authors.affiliation: Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, USA.
authors.forename: Sivagami Sundaram
authors.initials: SS
authors.lastname: Chavadi
authors.affiliation: Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, USA.
authors.forename: Uthamaphani R
authors.initials: UR
authors.lastname: Edupuganti
authors.affiliation: Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, USA Graduate Center, City University of New York, New York, New York, USA.
authors.forename: Poornima
authors.initials: P
authors.lastname: Mohandas
authors.affiliation: Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Chan
authors.affiliation: Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Zeng
authors.affiliation: Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, USA.
authors.forename: Mykhailo
authors.initials: M
authors.lastname: Kopylov
authors.affiliation: Department of Biochemistry and Milstein Chemistry Core Facility, Weill Cornell Medical College, New York, New York, USA.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Angelo
authors.affiliation: Department of Biochemistry and Milstein Chemistry Core Facility, Weill Cornell Medical College, New York, New York, USA.
authors.forename: J David
authors.initials: JD
authors.lastname: Warren
authors.affiliation: Department of Chemistry, Hunter College, City University of New York, New York, New York, USA.
authors.forename: Clifford E
authors.initials: CE
authors.lastname: Soll
authors.affiliation: Department of Biology, Brooklyn College, City University of New York, Brooklyn, New York, USA Graduate Center, City University of New York, New York, New York, USA LQuadri@brooklyn.cuny.edu.
authors.forename: Luis E N
authors.initials: LE
authors.lastname: Quadri
mesh_terms: D000213:Acyl Carrier Protein / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D006017:Glycolipids / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D009154:Mutation; D019910:Mycobacterium marinum / Q000235:genetics / Q000378:metabolism*; D010636:Phenols / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013045:Species Specificity
chemical_list: D000213:Acyl Carrier Protein; D001426:Bacterial Proteins; D006017:Glycolipids; D010636:Phenols