The SCO2299 gene from Streptomyces coelicolor A3(2) encodes a bifunctional enzyme consisting of an RNase H domain and an acid phosphatase domain.
The SCO2299 gene from Streptomyces coelicolor encodes a single peptide consisting of 497 amino acid residues. Its N-terminal region shows high amino acid sequence similarity to RNase HI, whereas its C-terminal region bears similarity to the CobC protein, which is involved in the synthesis of cobalamin. The SCO2299 gene suppressed a temperature-sensitive growth defect of an Escherichia coli RNase H-deficient strain, and the recombinant SCO2299 protein cleaved an RNA strand of RNA.DNA hybrid in vitro. The N-terminal domain of the SCO2299 protein, when overproduced independently, exhibited RNase H activity at a similar level to the full length protein. On the other hand, the C-terminal domain showed no CobC-like activity but an acid phosphatase activity. The full length protein also exhibited acid phosphatase activity at almost the same level as the C-terminal domain alone. These results indicate that RNase H and acid phosphatase activities of the full length SCO2299 protein depend on its N-terminal and C-terminal domains, respectively. The physiological functions of the SCO2299 gene and the relation between RNase H and acid phosphatase remain to be determined. However, the bifunctional enzyme examined here is a novel style in the Type 1 RNase H family. Additionally, S. coelicolor is the first example of an organism whose genome contains three active RNase H genes.
Ohtani
Naoto
N
Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan. nao10_oh@ybb.ne.jp
Saito
Natsumi
N
Tomita
Masaru
M
Itaya
Mitsuhiro
M
Itoh
Aya
A
D000135:Acid Phosphatase / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012329:RNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D016914:Ribonuclease H / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D048372:Streptomyces coelicolor / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D016914:Ribonuclease H; D000135:Acid Phosphatase