A Novel Transcriptional Regulator of CO Metabolism in Thermococcus onnurineus NA1

Abstract

The hyperthermophilic archaeon Thermococcus onnurineus NA1 is a hydrogenogenic carboxydotroph to have a gene cluster that encodes a carbon monoxide (CO)-oxidizing system. The cluster contains a gene encoding a putative regulator (rchA) which has a helix-turn-helix DNA-binding motif. RchA is phylogenetically distinguished from the known CO-dependent transcription regulators, CooA (CO oxidation activator) from Rhodospirillum rubrum or RcoM (regulator of CO metabolism) from Burkholderia xenovorans. RchA deletion mutant caused dominant growth inhibition in CO medium. RT-qPCR and western blotting showed that the levels of transcripts and proteins were not changed in the RchA deletion mutant whereas those were significantly increased in the wild type strain in the presence of CO. In this study, we present a new type of transcription regulator to regulate the expression of genes involved in the CO metabolism.which has a helix-turn-helix DNA-binding motif. RchA is phylogenetically distinguished from the known CO-dependent transcription regulators, CooA (CO oxidation activator) from Rhodospirillum rubrum or RcoM (regulator of CO metabolism) from Burkholderia xenovorans. RchA deletion mutant caused dominant growth inhibition in CO medium. RT-qPCR and western blotting showed that the levels of transcripts and proteins were not changed in the RchA deletion mutant whereas those were significantly increased in the wild type strain in the presence of CO. In this study, we present a new type of transcription regulator to regulate the expression of genes involved in the CO metabolism.