title: Genes involved in immunity to and secretion of aureocin A53, an atypical class II bacteriocin produced by Staphylococcus aureus A53.
abstract: Aureocin A53 is an antimicrobial peptide produced by Staphylococcus aureus A53. The genetic determinants involved in aureocin A53 production and immunity to its action are organized in at least four transcriptional units encoded by the 10.4-kb plasmid pRJ9. One transcriptional unit carries only the bacteriocin structural gene, aucA. No immunity gene is found downstream of aucA, as part of the same transcriptional unit. Further downstream of aucA is found an operon which contains the three genes aucEFG, whose products seem to associate to form a dedicated ABC transporter. When aucEFG were expressed in RN4220, an aureocin A53-sensitive S. aureus strain, this strain became partially resistant to the bacteriocin. A gene disruption mutant in aucE was defective in aureocin A53 externalization and more sensitive to aureocin A53 than the wild-type strain, showing that aucEFG are involved in immunity to aureocin A53 by active extrusion of the bacteriocin. Full resistance to aureocin A53 was exhibited by transformants carrying, besides aucEFG, the operon formed by two genes, aucIB and aucIA, located between aucA and aucEFG and carried in the opposite strand. AucIA and AucIB share similarities with hypothetical proteins not found in the gene clusters of other bacteriocins. A gene disruption mutant in orf8, located upstream of aucA and whose product exhibits about 50% similarity to a number of hypothetical membrane proteins found in many Gram-positive bacteria, was strongly affected in aureocin A53 externalization but resistant to aureocin A53, suggesting that Orf8 is also involved in aureocin A53 secretion.
authors.affiliation: Departamento de Microbiologia Geral, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Janaína Dos Santos
authors.initials: Jdos S
authors.lastname: Nascimento
authors.forename: Marcus Lívio Varella
authors.initials: ML
authors.lastname: Coelho
authors.forename: Hilana
authors.initials: H
authors.lastname: Ceotto
authors.forename: Amina
authors.initials: A
authors.lastname: Potter
authors.forename: Luana Rocha
authors.initials: LR
authors.lastname: Fleming
authors.forename: Zhian
authors.initials: Z
authors.lastname: Salehian
authors.forename: Ingolf F
authors.initials: IF
authors.lastname: Nes
authors.forename: Maria do Carmo de Freire
authors.initials: Mdo C
authors.lastname: Bastos
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001430:Bacteriocins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology; D001483:Base Sequence; D004926:Escherichia coli / Q000187:drug effects; D015870:Gene Expression; D005798:Genes, Bacterial; D009154:Mutation; D016366:Open Reading Frames; D009876:Operon; D010455:Peptides / Q000235:genetics* / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D013211:Staphylococcus aureus / Q000235:genetics* / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D001430:Bacteriocins; D010455:Peptides; C469333:aureocin A53, Staphylococcus aureus