title: Isolation of a variant of subtilosin A with hemolytic activity.
abstract: Bacillus subtilis produces an anionic bacteriocin called subtilosin A that possesses antibacterial activity against certain gram-positive bacteria. In this study, we uncovered a hemolytic mutant of B. subtilis that produces an altered form of subtilosin A. The mutant bacteriocin, named subtilosin A1, has a replacement of threonine at position 6 with isoleucine. In addition to the hemolytic activity, subtilosin A1 was found to exhibit enhanced antimicrobial activity against specific bacterial strains. The B. subtilis albB mutant that does not produce a putative immunity peptide was more sensitive to both subtilosin A and subtilosin A1. A spontaneous suppressor mutation of albB that restored resistance to subtilosin A and subtilosin A1 was obtained. The sbr (subtilosin resistance) mutation conferring the resistance is not linked to the sboA-alb locus. The sbr mutation does not increase the resistance of B. subtilis to other cell envelope-targeted antimicrobial agents, indicating that the mutation specifically confers the resistance to subtilosins. The findings suggest possible bioengineering approaches for obtaining anionic bacteriocins with enhanced and/or altered bactericidal activity. Furthermore, future identification of the subtilosin-resistant mutation could provide insights into the mechanism of subtilosin A activity.
authors.affiliation: Department of Science & Engineering, School of Medicine, Oregon Health & Science University, Beaverton, OR 97006, USA.
authors.forename: Tai
authors.initials: T
authors.lastname: Huang
authors.forename: Hao
authors.initials: H
authors.lastname: Geng
authors.forename: Venugopal R
authors.initials: VR
authors.lastname: Miyyapuram
authors.forename: Clarissa S
authors.initials: CS
authors.lastname: Sit
authors.forename: John C
authors.initials: JC
authors.lastname: Vederas
authors.forename: Michiko M
authors.initials: MM
authors.lastname: Nakano
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001430:Bacteriocins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006461:Hemolysis / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010456:Peptides, Cyclic / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology*; D011817:Rabbits
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins; D010456:Peptides, Cyclic; C047828:sboA protein, Bacillus subtilis