title: Dynamic Proteome Response of Pseudomonas aeruginosa to Tobramycin Antibiotic Treatment.
abstract: Genetically susceptible bacteria become antibiotic tolerant during chronic infections, and the mechanisms responsible are poorly understood. One factor that may contribute to differential sensitivity in vitro and in vivo is differences in the time-dependent tobramycin concentration profile experienced by the bacteria. Here, we examine the proteome response induced by subinhibitory concentrations of tobramycin in Pseudomonas aeruginosa cells grown under planktonic conditions. These efforts revealed increased levels of heat shock proteins and proteases were present at higher dosage treatments (0.5 and 1 μg/ml), while less dramatic at 0.1 μg/ml dosage. In contrast, many metabolic enzymes were significantly induced by lower dosages (0.1 and 0.5 μg/ml) but not at 1 μg/ml dosage. Time course proteome analysis further revealed that the increase of heat shock proteins and proteases was most rapid from 15 min to 60 min, and the increased levels sustained till 6 h (last time point tested). Heat shock protein IbpA exhibited the greatest induction by tobramycin, up to 90-fold. Nevertheless, deletion of ibpA did not enhance sensitivity to tobramycin. It seemed possible that the absence of sensitization could be due to redundant functioning of IbpA with other proteins that protect cells from tobramycin. Indeed, inactivation of two heat shock chaperones/proteases in addition to ibpA in double mutants (ibpA/clpB, ibpA/PA0779 and ibpA/hslV) did increase tobramycin sensitivity. Collectively, these results demonstrate the time- and concentration-dependent nature of the P. aeruginosa proteome response to tobramycin and that proteome modulation and protein redundancy are protective mechanisms to help bacteria resist antibiotic treatments.
authors.affiliation: From the ‡Department of Genome Sciences.
authors.forename: Xia
authors.initials: X
authors.lastname: Wu
authors.affiliation: From the ‡Department of Genome Sciences.
authors.forename: Kiara
authors.initials: K
authors.lastname: Held
authors.affiliation: §Department of Chemistry.
authors.forename: Chunxiang
authors.initials: C
authors.lastname: Zheng
authors.affiliation: ¶Department of Medicine and Microbiology, University of Washington, Seattle, WA 98195.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Staudinger
authors.affiliation: From the ‡Department of Genome Sciences.
authors.forename: Juan D
authors.initials: JD
authors.lastname: Chavez
authors.affiliation: From the ‡Department of Genome Sciences.
authors.forename: Chad R
authors.initials: CR
authors.lastname: Weisbrod
authors.affiliation: From the ‡Department of Genome Sciences.
authors.forename: Jimmy K
authors.initials: JK
authors.lastname: Eng
authors.affiliation: ¶Department of Medicine and Microbiology, University of Washington, Seattle, WA 98195.
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Singh
authors.affiliation: From the ‡Department of Genome Sciences.
authors.forename: Colin
authors.initials: C
authors.lastname: Manoil
authors.affiliation: From the ‡Department of Genome Sciences, §Department of Chemistry, jimbruce@u.washington.edu.
authors.forename: James E
authors.initials: JE
authors.lastname: Bruce
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism*; D063990:Gene Ontology; D008826:Microbial Sensitivity Tests; D017510:Protein Folding / Q000187:drug effects; D060066:Protein Interaction Maps / Q000187:drug effects; D020543:Proteome / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D015203:Reproducibility of Results; D013997:Time Factors; D014031:Tobramycin / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D020543:Proteome; D014031:Tobramycin