ompH gene expression is regulated by multiple environmental cues in addition to high pressure in the deep-sea bacterium Photobacterium species strain SS9.
Photobacterium species strain SS9 is a moderately barophilic (pressure-loving) deep-sea bacterial species which induces the expression of the ompH gene in response to elevated pressure. Here we demonstrate that at 1 atm (1 atm = 1.01325 x 10(5) Pa), ompH expression increases with cell density in 2216 marine medium batch culture and is subject to catabolite repression and the OmpH synthesis is inducible by energy (carbon) starvation. Regulatory mutants which are impaired in ompH gene expression at high pressure are also impaired in cell density regulation of ompH gene expression, indicating that the two inducing conditions overlap in their signal transduction pathways. The same promoter was activated by high cell density at 1 atm of pressure as well as during low-cell-density growth at 272 atm. Catabolite repression of ompH gene expression was induced by a variety of carbon sources, and this repression could be partially reversed in most cases by the addition of cyclic AMP (cAMP). Surprisingly, glucose repression of ompH transcription occurred only at 1 atm, not at 272 atm, despite the fact that catabolite repression was operational in SS9 under both conditions. It is suggested that ompH expression is cAMP and catabolite repressor protein dependent at 1 atm but becomes cAMP and perhaps catabolite repressor protein independent at 272 atm. Possible mechanisms of ompH gene activation are discussed.
Center for Marine Biomedicine and Biotechnology, Scripps Institution of Oceanography, University of California, San Diego, La Jolla 92093-0202.
D H
DH
Bartlett
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TJ
Welch
D001425:Bacterial Outer Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D001483:Base Sequence; D004734:Energy Metabolism; D015964:Gene Expression Regulation, Bacterial; D008386:Marine Biology; D008969:Molecular Sequence Data; D010776:Photobacterium / Q000235:genetics* / Q000254:growth & development; D010812:Physical Stimulation; D011312:Pressure; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015398:Signal Transduction; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014871:Water Microbiology
D001425:Bacterial Outer Membrane Proteins; D011993:Recombinant Fusion Proteins; C067128:ompH protein, bacteria