Pseudomonas aeruginosa lasR mutant fitness in microoxia is supported by an Anr-regulated oxygen-binding hemerythrin
Pseudomonas aeruginosa strains with loss-of-function mutations in the transcription factor LasR are frequently encountered in the clinic and the environment. Among the characteristics common to LasR-defective (LasR−) strains is increased activity of the transcription factor Anr, relative to their La...
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Published in | Proceedings of the National Academy of Sciences - PNAS Vol. 117; no. 6; pp. 3167 - 3173 |
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Main Authors | , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
National Academy of Sciences
11.02.2020
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Subjects | |
Online Access | Get full text |
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Summary: | Pseudomonas aeruginosa strains with loss-of-function mutations in the transcription factor LasR are frequently encountered in the clinic and the environment. Among the characteristics common to LasR-defective (LasR−) strains is increased activity of the transcription factor Anr, relative to their LasR+ counterparts, in low-oxygen conditions. One of the Anr-regulated genes found to be highly induced in LasR− strains was PA14_42860 (PA1673), which we named mhr for microoxic hemerythrin. Purified P. aeruginosa Mhr protein contained the predicted di-iron center and bound molecular oxygen with an apparent Kd
of ~1 μM. Both Anr and Mhr were necessary for fitness in lasR+ and lasR mutant strains in colony biofilms grown in microoxic conditions, and the effects were more striking in the lasR mutant. Among genes in the Anr regulon, mhr was most closely coregulated with the Anr-controlled high-affinity cytochrome c oxidase genes. In the absence of high-affinity cytochrome c oxidases, deletion of mhr no longer caused a fitness disadvantage, suggesting that Mhr works in concert with microoxic respiration. We demonstrate that Anr and Mhr contribute to LasR− strain fitness even in biofilms grown in normoxic conditions. Furthermore, metabolomics data indicate that, in a lasR mutant, expression of Anr-regulated mhr leads to differences in metabolism in cells grown on lysogeny broth or artificial sputum medium. We propose that increased Anr activity leads to higher levels of the oxygen-binding protein Mhr, which confers an advantage to lasR mutants in microoxic conditions. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Author contributions: M.E.C., J.H.H., F.Z., E.V.P., and D.A.H. designed research; M.E.C., J.H.H., F.Z., X.C., and M.S.P. performed research; M.E.C., J.H.H., F.Z., and C.H.K. contributed new reagents/analytic tools; M.E.C., J.H.H., F.Z., X.C., C.H.K., A.J.L., T.H.H., C.S.G., E.V.P., and D.A.H. analyzed data; and M.E.C., J.H.H., F.Z., C.S.G., E.V.P., and D.A.H. wrote the paper. 1M.E.C. and J.H.H. contributed equally to this work. Edited by Dianne K. Newman, California Institute of Technology, Pasadena, CA, and approved December 28, 2019 (received for review October 11, 2019) |
ISSN: | 0027-8424 1091-6490 |
DOI: | 10.1073/pnas.1917576117 |