title: Membrane proteases and aminoglycoside antibiotic resistance.
abstract: We present genetic studies that help define the functional network underlying intrinsic aminoglycoside resistance in Pseudomonas aeruginosa. Our analysis shows that proteolysis, particularly that controlled by the membrane protease FtsH, is a major determinant of resistance. First, we examined the consequences of inactivating genes controlled by AmgRS, a two-component regulator required for intrinsic tobramycin resistance. Three of the gene products account for resistance: a modulator of FtsH protease (YccA), a membrane protease (HtpX), and a membrane protein of unknown function (PA5528). Second, we screened mutations inactivating 66 predicted proteases and related functions. Insertions inactivating two FtsH protease accessory factors (HflK and HflC) and a cytoplasmic protease (HslUV) increased tobramycin sensitivity. Finally, we generated an ftsH deletion mutation. The mutation dramatically increased aminoglycoside sensitivity. Many of the functions whose inactivation increased sensitivity appeared to act independently, since multiple mutations led to additive or synergistic effects. Up to 500-fold increases in tobramycin sensitivity were observed. Most of the mutations also were highly pleiotropic, increasing sensitivity to a membrane protein hybrid, several classes of antibiotics, alkaline pH, NaCl, and other compounds. We propose that the network of proteases provides robust protection from aminoglycosides and other substances through the elimination of membrane-disruptive mistranslation products.
authors.affiliation: Department of Genome Sciences, University of Washington, Campus Box 355065, 1705 NE Pacific St., Seattle, WA 98195, USA.
authors.forename: Aaron
authors.initials: A
authors.lastname: Hinz
authors.forename: Samuel
authors.initials: S
authors.lastname: Lee
authors.forename: Kyle
authors.initials: K
authors.lastname: Jacoby
authors.forename: Colin
authors.initials: C
authors.lastname: Manoil
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000201:enzymology*; D024881:Drug Resistance, Bacterial; D055786:Gene Knockout Techniques; D008826:Microbial Sensitivity Tests; D016254:Mutagenesis, Insertional; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D010447:Peptide Hydrolases