The Transcription Factor CoxR Negatively Regulates Alkane Hydroxylase Transcription

Both gram negative and gram positive bacteria have enzymes for metabolizing alkanes. The alpha proteobacteria Caulobacter crescentus has a medium-chain alkane hydroxylase that is a member of the CYP153 family of cytochrome P450 enzymes. The molecular mechanism controlling transcription of this hydroxylase has not been described. We carried out a reverse genetics screen and RNA-seq to find the transcription factor regulating this alkane hydroxylase. A deletion of the transcription factor, named CoxR, resulted in upregulation of both the alkane hydroxylase as well as ferredoxin and ferredoxin reductase enzymes. Gel shift assays demonstrated that CoxR bound directly to the promoter of the alkane hydroxylase. In conclusion, we have identified a novel transcription factor involved in metabolism of alkanes.