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Edited* by Susan Gottesman, National Cancer Institute, Bethesda, MD, and approved July 20, 2010 (received for review June 3, 2010)
Abstract
Siderophores are essential factors for iron (Fe) acquisition in bacteria during colonization and infection of eukaryotic hosts, which restrain iron access through iron-binding protein, such as lactoferrin and transferrin. The synthesis of siderophores by Escherichia coli is considered to be fully regulated at the transcriptional level by the Fe-responsive transcriptional repressor Fur. Here we characterized two different pathways that promote the production of the siderophore enterobactin via the action of the small RNA RyhB. First, RyhB is required for normal expression of an important enterobactin biosynthesis polycistron, entCEBAH. Second, RyhB directly represses the translation of cysE, which encodes a serine acetyltransferase that uses serine as a substrate for cysteine biosynthesis. Reduction of CysE activity by RyhB allows serine to be used as building blocks for enterobactin synthesis through the nonribosomal peptide synthesis pathway. Thus, RyhB plays an essential role in siderophore production and may modulate bacterial virulence through optimization of siderophore production.
Footnotes
- 1To whom correspondence should be addressed. E-mail: eric.masse{at}usherbrooke.ca.
Author contributions: H.S., J.M.S., M.C., M.E.S.M., C.M.D., J.I., and E.M. designed research; H.S., P.L.-B., J.M.S., M.C., J.-A.M.B., M.E.S.M., F.L., C.M.D., and J.I. performed research; H.S., P.L.-B., J.M.S., M.C., J.-A.M.B., M.E.S.M., F.L., C.M.D., and J.I. contributed new reagents/analytic tools; H.S., P.L.-B., J.M.S., M.C., J.-A.M.B., M.E.S.M., F.L., C.M.D., J.I., and E.M. analyzed data; and H.S., C.M.D., J.I., and E.M. wrote the paper.
The authors declare no conflict of interest.
↵*This Direct Submission article had a prearranged editor.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1007805107/-/DCSupplemental.
A small RNA promotes siderophore production through transcriptional and metabolic remodeling
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