# High-throughput Sequencing Reveals Suppressors of Vibrio cholerae rpoE Mutations: One Fewer Porin is Enough

 Title: High-throughput Sequencing Reveals Suppressors of Vibrio cholerae rpoE Mutations: One Fewer Porin is Enough Author: Davis, Brigid; Waldor, Matthew K Note: Order does not necessarily reflect citation order of authors. Citation: Davis, Brigid M., and Matthew K. Waldor. 2009. High-throughput sequencing reveals suppressors of Vibrio cholerae rpoE mutations: One fewer porin is enough. Nucleic Acids Research 37(17): 5757-5767. Full Text & Related Files: 2761261.pdf (1.731Mb; PDF) Abstract: Analyses of suppressor mutations have been extremely valuable in understanding gene function. However, techniques for mapping suppressor mutations are not available for most bacterial species. Here, we used high-throughput sequencing technology to identify spontaneously arising suppressor mutations that enabled disruption of rpoE (which encodes σ$$^E$$) in Vibrio cholerae, the agent of cholera. The alternative sigma factor σ$$^E$$, which is activated by envelope stress, promotes expression of factors that help preserve and/or restore cell envelope integrity. In Escherichia coli, rpoE is an essential gene that can only be disrupted in the presence of additional suppressor mutations. Among a panel of independent V. cholerae rpoE mutants, more than 75% contain suppressor mutations that reduce production of OmpU, V. cholerae’s principal outer membrane porin. OmpU appears to be a key determinant of V. cholerae’s requirement for and production of σ$$^E$$. Such dependence upon a single factor contrasts markedly with regulation of σ$$^E$$ in E. coli, in which numerous factors contribute to its activation and none is dominant. We also identified a suppressor mutation that differs from all previously described suppressors in that it elevates, rather than reduces, σ$$^E$$’s activity. Finally, analyses of a panel of rpoE mutants shed light on the mechanisms by which suppressor mutations may arise in V. cholerae. Published Version: doi://10.1093/nar/gkp568 Other Sources: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2761261/pdf/ Terms of Use: This article is made available under the terms and conditions applicable to Other Posted Material, as set forth at http://nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of-use#LAA Citable link to this page: http://nrs.harvard.edu/urn-3:HUL.InstRepos:5336036