title: Molecular genetic analysis of a locus required for resistance to antimicrobial peptides in Salmonella typhimurium.
abstract: The innate immunity of vertebrates and invertebrates to microbial infection is mediated in part by small cationic peptides with antimicrobial activity. Successful pathogens have evolved mechanisms to withstand the antibiotic activity of these molecules. We have isolated a set of genes from Salmonella typhimurium which are required for virulence and resistance to the antimicrobial peptides melittin and protamine. Sequence analysis of a 5.7 kb segment from the wild-type plasmid conferring resistance to protamine contained five open reading frames: sapA, sapB, sapC, sapD and sapF, organized in an operon structure and transcribed as a 5.3 kb mRNA. SapD and SapF exhibited similarity with the 'ATP binding cassette' family of transporters including the bacterial Opp and SpoOK, involved in the uptake of oligopeptides; the yeast STE6, necessary for the export of a peptide pheromone; and the mammalian mdr, which mediates resistance to chemotherapeutic agents in cancer cells. SapA showed identity with other periplasmic solute binding proteins involved in peptide transport. The SapABCDF system constitutes a novel transporter for enteric bacteria and the first one harboring a periplasmic component with a role in virulence.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110.
authors.forename: C
authors.initials: C
authors.lastname: Parra-Lopez
authors.forename: M T
authors.initials: MT
authors.lastname: Baer
authors.forename: E A
authors.initials: EA
authors.lastname: Groisman
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001483:Base Sequence; D001692:Biological Transport; D003001:Cloning, Molecular; D004352:Drug Resistance, Microbial / Q000235:genetics; D004755:Enterobacteriaceae / Q000235:genetics; D005798:Genes, Bacterial; D008555:Melitten / Q000494:pharmacology; D008954:Models, Biological; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics; D010455:Peptides; D011479:Protamines / Q000494:pharmacology; D012486:Salmonella typhimurium / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D010455:Peptides; D011479:Protamines; D008555:Melitten; D000255:Adenosine Triphosphate