title: Positive regulation of the Shewanella oneidensis OmpS38, a major porin facilitating anaerobic respiration, by Crp and Fur.
abstract: Major porins are among the most abundant proteins embedded in the outer membrane (OM) of Gram-negative bacteria, playing crucial roles in maintenance of membrane structural integrity and OM permeability. Although many OM proteins (especially c-type cytochromes) in Shewanella oneidensis, a research model for respiratory versatility, have been extensively studied, physiological significance of major porins remains largely unexplored. In this study, we show that OmpS38 and OmpA are two major porins, neither of which is responsive to changes in osmolarity or contributes to the intrinsic resistance to β-lactam antibiotics. However, OmpS38 but not OmpA is largely involved in respiration of non-oxygen electron acceptors. We then provide evidence that expression of ompS38 is transcribed from two promoters, the major of which is favored under anaerobic conditions while the other appears constitutive. The major promoter is under the direct control of Crp, the master regulator dictating respiration. As a result, the increase in the level of OmpS38 correlates with an elevated activity in Crp under anaerobic conditions. In addition, we show that the activity of the major promoter is also affected by Fur, presumably indirectly, the transcription factor for iron-dependent gene expression.
authors.affiliation: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Gao
authors.affiliation: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Ju
authors.affiliation: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Yin
authors.affiliation: Institute of Microbiology and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
authors.forename: Haichun
authors.initials: H
authors.lastname: Gao
mesh_terms: D000693:Anaerobiosis; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D004058:Diffusion; D015964:Gene Expression Regulation, Bacterial; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009573:Nitrites / Q000378:metabolism; D018272:Porins / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D020592:Shewanella / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D024363:Transcription Initiation Site; D015533:Transcriptional Activation
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D009573:Nitrites; D018272:Porins; C078167:OMPA outer membrane proteins