고세균 써모코커스 온누리누스 엔에이 원으로부터 히스티디놀 인산 분해 효소

Abstract

The entire gene cluster encoding enzymes involved in the histidine biosynthesis was analyzed in the complete genome of the hyperthermophilic archaeon Thermococcus onnurineus NA1 and it was found that an essential gene to encode the histidinol phosphate phosphatase (EC 3.1.3.15), catalyzing the eighth step of the pathway, was not assigned. A gene, which was annotated as a predicted hydrolase belonging to the haloacid dehalogenase superfamily, was speculated to specify the enzyme because it located next to the histidinol phosphate aminotransferase, which is a member of gene cluster. The gene was cloned and expressed in Escherichia coli. The recombinant enzyme exhibited Co2+-, Mg2+-, Mn2+-, or Ni2+-dependent phosphatase activity for AMP, phosphoserine, and fructose-6-phosphate among various substrates for other phosphatases. The implication of the gene to encode histidinol phosphate phosphatase was strongly supported by kinetic analysis. The catalytic efficiency for histidinol phosphate was two or three order of magnitude higher than those for the above three substrates. The orthologs were also observed in the other hyperthermophilic archaea, Thermococcus kodakaraensis (56.4% identity) and Pyrococcus furiosus.