Mechanistic dissection of pseudomonas aeruginosa anaerobic respiration : implications for treatment of cystic fibrosis airway disease.
Year: 2004
Type: article
Abstract: Pseudomonas aeruginosa is an opportunistic pathogen that causes chronic lung infection in cystic fibrosis (CF) patients.During the course of infection, P. aeruginosa develops biofilms that are resistant to antibiotic treatment and undergoes a phenotypic switch to a mucoid alginate-overproducing form.Due to the hyperabsorption of airway surface liquid caused by a defective or absent cystic fibrosis transmembrane conductance regulator (CFTR), bacterial infection ensues.Recently, the CF mucus lining the airway was determined to be anaerobic.In addition, the mucus layer becomes acidic because of abnormal bicarbonate transport across the airway epithelium.During in vitro anaerobic biofilm growth, P. aeruginosa formed ~7-fold more biofilm compared to those developed aerobically, supporting the idea that CF pathogenesis is associated with bacterial biofilm formation under anaerobic conditions.We discovered that defects leading to overproduction of nitric oxide (NO) resulted in significant decrease in viability under such conditions.Major contributors that minimized NO-mediated damage were found to be (i) quorum sensing circuitry, (ii) NO reductase (a ma jor NO detoxifier in P. aeruginosa) and (iii) anti-sigma factor, MucA, that is required for full activity of NO reductase.However, in a norCB mutant where abnormally high levels of NO accumulate during anaerobic respiration, a master anaerobic regulator, ANR, senses NO through its [4Fe-4S] 2+ cluster and, thus, inhibits further production of NO.Simultaneoulsy, high levels of NO in this mutant were scavenged by two Fe-cofactored enzymes, the synthesis of which was stimulated at the result of ANR inactivatio n.We have also shown that nitrite (NO 2 -) can selectively kill mucoid mucA mutant P. aeruginosa at a slightly acidic pH that mimics the CF airway.The mucA mutant harbored negligible nitrite reductase i II.C. Materials and Methods……………………………………………………..41 II.D. Results…………………………………………………………….………..45 Robust P. aeruginosa Biofilm Formation during Anaerobic Versus Aerobic Conditions…………………………......45 Which Gene Products Are Required for Anaerobic, as Compared with Aerobic, Biofilms?……………………………...48 Gene Products Essential for Optimal Viability in Anaerobic Biofilms……………………………………………...50 Death of Anaerobic QS Mutants in a Biofilm Is Due to Metabolic Intoxication by Nitric Oxide (NO)……………...52 Aerobic Versus Anaerobic Biofilm Proteomics: A Link Found to Differences in Overall Biofilm Physiology………………57 CF Patients with Chronic P. aeruginosa Infections Have Lung Secretions Harboring, and Raise Antibodies to, OprF.............63 Role of OprF in Anaerobic Growth and NO 2 -Reductase Activity……………………………………………………………..66 II.E. Discussion…………………………………………………………………...72 II.F. Acknowledgements…………………………………………………....
Author: Sang Sun Yoon
Institution: University of Cincinnati
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2279140280