Linearized Siderophore Products Secreted via MacAB Efflux Pump Protect Salmonella enterica Serovar Typhimurium from Oxidative Stress.

Autor: Bogomolnaya LM; Texas A&M University Health Science Center, Bryan, Texas, USA.; Institute of Fundamental Medicine and Biology, Kazan Federal (Volga Region) University, Kazan, Russia.; Marshall University Joan C. Edwards School of Medicine, Huntington, West Virginia, USA., Tilvawala R; Texas A&M University Health Science Center, Bryan, Texas, USA.; University of Massachusetts Medical School, Worcester, Massachusetts, USA., Elfenbein JR; North Carolina State University College of Veterinary Medicine, Raleigh, North Carolina, USA.; University of Wisconsin School of Veterinary Medicine, Madison, Wisconsin, USA., Cirillo JD; Texas A&M University Health Science Center, Bryan, Texas, USA., Andrews-Polymenis HL; Texas A&M University Health Science Center, Bryan, Texas, USA handrews@tamu.edu.
Jazyk: angličtina
Zdroj: MBio [mBio] 2020 May 05; Vol. 11 (3). Date of Electronic Publication: 2020 May 05.
DOI: 10.1128/mBio.00528-20
Abstrakt: Nontyphoidal salmonellae (NTS) are exposed to reactive oxygen species (ROS) during their residency in the gut. To survive oxidative stress encountered during infection, salmonellae employ several mechanisms. One of these mechanisms involves the multidrug efflux pump MacAB, although the natural substrate of this pump has not been identified. MacAB homologs in pseudomonads secrete products of nonribosomal peptide synthesis (NRPS). In Salmonella enterica serovar Typhimurium, the siderophore enterobactin is produced by NRPS in response to iron starvation and this molecule can be processed into salmochelin and several linear metabolites. We found that Salmonella mutants lacking the key NRPS enzyme EntF are sensitive to peroxide mediated killing and cannot detoxify extracellular H 2 O 2 Moreover, EntF and MacAB function in a common pathway to promote survival of Salmonella during oxidative stress. We further demonstrated that S. Typhimurium secretes siderophores in iron-rich media when peroxide is present and that these MacAB-secreted metabolites participate in protection of bacteria against H 2 O 2 We showed that secretion of anti-H 2 O 2 molecules is independent of the presence of the known siderophore efflux pumps EntS and IroC, well-described efflux systems involved in secretion of enterobactin and salmochelin. Both salmochelin and enterobactin are dispensable for S. Typhimurium protection against ROS; however, linear metabolites of enterobactin produced by esterases IroE and Fes are needed for bacterial survival in peroxide-containing media. We determined that linearized enterobactin trimer protects S. Typhimurium against peroxide-mediated killing in a MacAB-dependent fashion. Thus, we suggest that linearized enterobactin trimer is a natural substrate of MacAB and that its purpose is to detoxify extracellular reactive oxygen species. IMPORTANCE Nontyphoidal Salmonella bacteria induce a classic inflammatory diarrhea by eliciting a large influx of neutrophils, producing a robust oxidative burst. Despite substantial progress understanding the benefits to the host of the inflammatory response to Salmonella , little is known regarding how Salmonella can simultaneously resist the damaging effects of the oxidative burst. The multidrug efflux pump MacAB is important for survival of oxidative stress both in vitro and during infection. We describe a new pathway used by Salmonella Typhimurium to detoxify extracellular reactive oxygen species using a multidrug efflux pump (MacAB) to secrete a linear siderophore, a metabolite of enterobactin. The natural substrates of many multidrug efflux pumps are unknown, and functional roles of the linear metabolites of enterobactin are unknown. We bring two novel discoveries together to highlight an important mechanism used by Salmonella to survive under the oxidative stress conditions that this organism encounters during the classic inflammatory diarrhea that it also induces.
(Copyright © 2020 Bogomolnaya et al.)
Databáze: MEDLINE
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