title: Self-resistance and cell wall composition in the glycopeptide producer Amycolatopsis balhimycina.
abstract: The prevailing resistance mechanism against glycopeptides in Gram-positive pathogens involves reprogramming the biosynthesis of peptidoglycan precursors, resulting in d-alanyl-d-lactate depsipeptide termini. Amycolatopsis balhimycina produces the vancomycin-like glycopeptide balhimycin and therefore has to protect itself from the action of the glycopeptide. We studied the roles of the accessory resistance gene orthologs vanY(b), vnlR(b), and vnlS(b), which are part of the balhimycin biosynthetic gene cluster (represented by the subscript "b"). The VanY(b) carboxypeptidase cleaved the terminal d-Ala from peptidoglycan precursors, and its heterologous expression enhanced glycopeptide resistance in Streptomyces coelicolor. The VanRS-like two component system VnlRS(b) was not involved in glycopeptide resistance or in the expression of the vanHAX glycopeptide resistance genes. Mature A. balhimycina peptidoglycan contained mainly tri- and tetrapeptides, with only traces of the d-Ala-d-Ala-ending pentapeptides that are binding sites for the antibiotic produced. The structure of the peptidoglycan precursor is consistent with the presence of vanHAX genes, which were identified outside the balhimycin synthesis cluster. Both wild-type and non-antibiotic-producing mutant strains synthesized peptidoglycan precursors ending mainly with d-Lac, indicating constitutive synthesis of a resistant cell wall. A. balhimycina could provide a model for an ancestral glycopeptide producer with constitutively expressed resistance genes.
authors.affiliation: Eberhard-Karls-Universität Tübingen, Interfakultäres Institut für Mikrobiologie und Infektionsmedizin (IMIT), Mikrobiologie/Biotechnologie, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
authors.forename: Till F
authors.initials: TF
authors.lastname: Schäberle
authors.forename: Waldemar
authors.initials: W
authors.lastname: Vollmer
authors.forename: Hans-Jörg
authors.initials: HJ
authors.lastname: Frasch
authors.forename: Stephan
authors.initials: S
authors.lastname: Hüttel
authors.forename: Andreas
authors.initials: A
authors.lastname: Kulik
authors.forename: Marlene
authors.initials: M
authors.lastname: Röttgen
authors.forename: Anna-Katharina
authors.initials: AK
authors.lastname: von Thaler
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wohlleben
authors.forename: Evi
authors.initials: E
authors.lastname: Stegmann
mesh_terms: D000192:Actinomycetales / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006020:Glycopeptides / Q000378:metabolism*; D013058:Mass Spectrometry; D005810:Multigene Family / Q000235:genetics; D010457:Peptidoglycan / Q000378:metabolism; D014640:Vancomycin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D006020:Glycopeptides; D010457:Peptidoglycan; C087127:balhimycin; D014640:Vancomycin