title: Structural characterization of four prochlorosins: a novel class of lantipeptides produced by planktonic marine cyanobacteria.
abstract: Prochlorosins make up a class of secondary metabolites produced by strains of Prochlorococcus, single-cell, planktonic marine cyanobacteria. These polycyclic peptides contain lanthionine and methyllanthionine residues that result in thioether cross-links. In Prochlorococcus MIT9313, a single enzyme, ProcM, catalyzes the posttranslational modification of 29 linear peptide substrates to generate a library of highly diverse cyclic peptides. To investigate the catalytic promiscuity of ProcM, we chose four prochlorosins previously demonstrated to be produced by the organism for detailed structural characterization. Nuclear magnetic resonance studies allowed unambiguous assignment of the ring topologies, demonstrating a high degree of topological diversity. The stereochemistry of the lanthionine and methyllanthionine residues was determined by gas chromatography and mass spectrometry for seven prochlorosins. All methyllanthionines had the (2S,3S,6R) configuration, and the lanthionines had the (2S,6R) configuration, irrespective of the direction of cyclization, ring size, or ring topology. These findings indicate that most, if not all, of the rings in prochlorosins are formed enzymatically by ProcM lanthionine synthetase and not by a nonenzymatic process as previously suggested.
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Weixin
authors.initials: W
authors.lastname: Tang
authors.forename: Wilfred A
authors.initials: WA
authors.lastname: van der Donk
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives / Q000737:chemistry; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000145:classification; D008401:Gas Chromatography-Mass Spectrometry; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010456:Peptides, Cyclic / Q000096:biosynthesis / Q000737:chemistry* / Q000145:classification; D048929:Prochlorococcus / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D017386:Sequence Homology, Amino Acid; D013237:Stereoisomerism; D013440:Sulfides / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D010456:Peptides, Cyclic; D013440:Sulfides; C001520:lanthionine; D000409:Alanine