title: Investigation of the substrate specificity of lacticin 481 synthetase by using nonproteinogenic amino acids.
abstract: Lantibiotics are peptide antimicrobial compounds that are characterized by the thioether-bridged amino acids lanthionine and methyllanthionine. For lacticin 481, these structures are installed in a two-step post-translational modification process by a bifunctional enzyme, lacticin 481 synthetase (LctM). LctM catalyzes the dehydration of Ser and Thr residues to generate dehydroalanine or dehydrobutyrine, respectively, and the subsequent intramolecular regio- and stereospecific Michael-type addition of cysteines onto the dehydroamino acids. In this study, semisynthetic substrates containing nonproteinogenic amino acids were prepared by expressed protein ligation and [3+2]-cycloaddition of azide and alkyne-functionalized peptides. LctM demonstrated broad substrate specificity toward substrates containing beta-amino acids, D-amino acids, and N-alkyl amino acids (peptoids) in certain regions of its peptide substrate. These findings showcase its promise for use in lantibiotic and peptide-engineering applications, whereby nonproteinogenic amino acids might impart improved stability or modulated biological activities. Furthermore, LctM permitted the incorporation of an alkyne-containing amino acid that can be utilized for the site-selective modification of mature lantibiotics and used in target identification.
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, Howard Hughes Medical Institute, 600 S. Mathews Avenue, Urbana, IL 61801, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Levengood
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Kerwood
authors.forename: Champak
authors.initials: C
authors.lastname: Chatterjee
authors.forename: Wilfred A
authors.initials: WA
authors.lastname: van der Donk
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D001430:Bacteriocins / Q000378:metabolism*; D004798:Enzymes / Q000378:metabolism*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D004798:Enzymes; C481644:LctM protein, Lactococcus lactis; D010455:Peptides; C082508:lacticin 481