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| The EMBO Journal
(2000) 19, 4237–4247, doi:10.1093/emboj/19.16.4237 |
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| Redox signaling: globalization of gene expression |
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| Jeong-II Oh and Samuel Kaplan |
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Department of Microbiology and Molecular Genetics, The University of Texas Health Science Center, Medical School, 6431 Fannin, Houston, TX 77030, USA To whom correspondence should be addressed Samuel Kaplan, skaplan@utmmg.med.uth.tmc.edu Received 19 April 2000; Revised 14 June 2000; Accepted 30 June 2000. |
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| Abstract |
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| Here we show that the extent of electron flow through the cbb3 oxidase of Rhodobacter sphaeroides is inversely related to the expression levels of those photosynthesis genes that are under control of the PrrBA two-component activation system: the greater the electron flow, the stronger the inhibitory signal generated by the cbb3 oxidase to repress photosynthesis gene expression. Using site-directed mutagenesis, we show that intramolecular electron transfer within the cbb3 oxidase is involved in signal generation and transduction and this signal does not directly involve the intervention of molecular oxygen. In addition to the cbb3 oxidase, the redox state of the quinone pool controls the transcription rate of the puc operon via the AppA–PpsR antirepressor–repressor system. Together, these interacting regulatory circuits are depicted in a model that permits us to understand the regulation by oxygen and light of photosynthesis gene expression in R.sphaeroides. |
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| Keywords: cbb3 cytochrome c oxidase, electron transport chain, gene regulation, photosynthesis, redox sensing |
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