{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,23]],"date-time":"2026-08-23T16:26:03Z","timestamp":1787502363390,"version":"build-2736575974"},"reference-count":28,"publisher":"Public Library of Science (PLoS)","issue":"1","license":[{"start":{"date-parts":[[2024,1,2]],"date-time":"2024-01-02T00:00:00Z","timestamp":1704153600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000009","name":"Foundation for the National Institutes of Health","doi-asserted-by":"publisher","award":["R01 GM 122947"],"award-info":[{"award-number":["R01 GM 122947"]}],"id":[{"id":"10.13039\/100000009","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS ONE"],"abstract":"\n The gram-negative bacterium\n Bradyrhizobium japonicum<\/jats:italic>\n can take up structurally dissimilar ferric siderophores from the environment (xenosiderophores) to meet its nutritional iron requirements. Siderophore-bound iron transported into the periplasm is reduced to the ferrous form by FsrB, dissociated from the siderophore and the free ion is then transported into the cytoplasm by the ferrous iron transporter FeoAB. Here, we identified the RND family exporter genes\n exsFG<\/jats:italic>\n and\n exsH<\/jats:italic>\n in a selection for secondary site suppressor mutants that restore growth of an\n fsrB<\/jats:italic>\n mutant on the siderophores ferrichrome or ferrioxamine. The low level of radiolabel accumulation from\n 55<\/jats:sup>\n Fe-labeled ferrichrome or ferrioxamine observed in the\n fsrB<\/jats:italic>\n mutant was restored to wild type levels in the\n fsrB exsG<\/jats:italic>\n mutant. Moreover, the\n exsG<\/jats:italic>\n mutant accumulated more radiolabel from the\n 55<\/jats:sup>\n Fe-labeled siderophores than the wild type, but radiolabel accumulation from inorganic\n 55<\/jats:sup>\n Fe was similar in the two strains. Thus, ExsFGH exports siderophore-bound iron, but not inorganic iron. The rescued\n fsrB<\/jats:italic>\n exsG mutant required\n feoB<\/jats:italic>\n for growth, indicating that ExsFGH acts on those siderophores in the periplasm. The\n exsG<\/jats:italic>\n mutant was more sensitive to the siderophore antibiotic albomycin than the wild type, whereas the\n fsrB<\/jats:italic>\n mutant was more resistant. This suggests ExsFGH normally exports ferrated albomycin.\n B<\/jats:italic>\n .\n japonicum<\/jats:italic>\n is naturally resistant to many antibiotics. The\n exsG<\/jats:italic>\n strain was very sensitive to tetracycline, but not to six other antibiotics tested. We conclude that ExsFGH is a broad substrate exporter that is needed to maintain siderophore homeostasis in the periplasm.\n <\/jats:p>","DOI":"10.1371\/journal.pone.0296306","type":"journal-article","created":{"date-parts":[[2024,1,2]],"date-time":"2024-01-02T15:04:21Z","timestamp":1704207861000},"page":"e0296306","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":2,"title":["The Bradyrhizobium japonicum exporter ExsFGH is involved in efflux of ferric xenosiderophores from the periplasm"],"prefix":"10.1371","volume":"19","author":[{"given":"Alasteir","family":"Ong","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5196-7594","authenticated-orcid":true,"given":"Mark 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