Studies on transcriptional regulators involved in H2 production in the hyperthermophilic archaeon Thermococcus onnurineus NA1

Abstract

The hyperthermophilic archaeon Thermococcus onnurineus NA1, isolated from a deep-sea hydrothermal vent, has been studied as a hydrogen (H2) producer using carbon monoxide, formate, pyruvate, or glucose as substrates. Several transcriptional regulators controlling H2-producing metabolisms have been identified in T. onnurineus NA1. SurR, sulfur response regulator, was identified to activate transcription of the mbh (membrane-bound hydrogenase) and mfh2 (membrane-bound formate-dependent hydrogenase 2) gene clusters. The transcriptional regulators, CorQR (CO responsive regulatory system) and EnfR ('eighth note' fold regulator), activate and repress, respectively, the carbon monoxide dehydrogenase (CODH) gene cluster, which is involved in H2 production from carbon monoxide. Two genes, TON_1797 and TON_0332, are homologs of genes encoding TrmB (transcriptional regulator of mal operon)-like proteins. TON_1797 homologs, termed TrmBL1 or Tgr (Thermococcales glycolytic regulator), have been identified as sugar-sensing transcriptional regulators of genes encoding glycolytic or gluconeogenic enzymes and sugar transport systems. TON_0332 homologs, termed TrmBL2, have been postulated to play as a general chromosomal protein agglutinating DNA to thick fibrous structures. To understand the function of TON_1797 and TON_0332 in relation to H2 production, we constructed gene disruption mutants and investigated their physiological properties under different culture conditions.