CO에 반응하는 새로운 전사 조절자와 이를 이용한 T. onnurineus NA1의 수소 생산성 증가

Abstract

Genome analysis of carboxydotrophic hydrogenogenic Thermococcus onnurineus NA1 revealed the existence of a putative transcriptional regulator system composed of CorQ with a V4R domain and CorR with a DNA-binding domain of LTTR family in close proximity to CO dehydrogenase (CODH) gene cluster. Homologous genes for the CorQR pairs were only found in Thermococcus species and Candidatus Korarchaeum cryptofilum OPF8. In-frame deletion of corQ or corR caused a severe impairment in CO-dependent growth and H2 production, suggesting that corQR encodes positive regulatory proteins essential for the expression of a CODH gene cluster. Introduction and expression of corQR genes under the control of a strong promoter in the corR-deletion strain, significantly increased mRNA and protein levels of the CODH gene relative to the wild-type strain. In a bioreactor culture, the ΔCorR/corQR↑ strain exhibited a 5.8-fold higher maximum H2 production rate than did the wild-type strain. To the best of our knowledge, this engineered strain has the highest H2 production rate, 191.9 mmol liter-1 h-1, and specific H2 production rate, 249.6 mmol g-1 h-1, higher than any CO-dependent H2-producing prokaryote reported so far. This study presents the first example of a transcriptional regulator system acting as a pair in the regulation of CO metabolism.lose proximity to CO dehydrogenase (CODH) gene cluster. Homologous genes for the CorQR pairs were only found in Thermococcus species and Candidatus Korarchaeum cryptofilum OPF8. In-frame deletion of corQ or corR caused a severe impairment in CO-dependent growth and H2 production, suggesting that corQR encodes positive regulatory proteins essential for the expression of a CODH gene cluster. Introduction and expression of corQR genes under the control of a strong promoter in the corR-deletion strain, significantly increased mRNA and protein levels of the CODH gene relative to the wild-type strain. In a bioreactor culture, the ΔCorR/corQR↑ strain exhibited a 5.8-fold higher maximum H2 production rate than did the wild-type strain. To the best of our knowledge, this engineered strain has the highest H2 production rate, 191.9 mmol liter-1 h-1, and specific H2 production rate, 249.6 mmol g-1 h-1, higher than any CO-dependent H2-producing prokaryote reported so far. This study presents the first example of a transcriptional regulator system acting as a pair in the regulation of CO metabolism.