Genetic and biochemical characterization of a protein phosphatase with dual substrate specificity in Streptomyces coelicolor A3(2).
A gene encoding a protein phosphatase (SppA) with a phosphoesterase motif, which was predicted by the genome project of the Gram-positive bacterium Streptomyces coelicolor A3(2), was cloned by PCR in pET32a(+) and expressed in Escherichia coli. SppA fused to thioredoxin (TRX-SppA) showed distinct heat-stable phosphatase activity toward p-nitrophenyl phosphate with optimal pH 8.0 and optimal temperature 55 degrees C. Mn2+ greatly enhanced enzyme activity, as is found with other protein Ser/Thr phosphatases. TRX-SppA was not inhibited by sodium orthovanadate or okadaic acid, both of which are known to be specific inhibitors of protein phosphatases. TRX-SppA showed phosphatase activity toward not only phosphoThr (pThr) and pTyr but also oligopeptides containing pSer, pThr, and pTyr, indicating that SppA is a protein phosphatase with dual substrate specificity. Disruption of the chromosomal sppA gene resulted in severe impairment of vegetative growth. All of these observations show that SppA, a protein phosphatase with dual specificity, plays an important, but not essential, role in vegetative growth of S. coelicolor A3(2). The presence of a single copy of sppA in all the 13 Streptomyces species examined, as determined by Southern hybridization, suggests a common role of SppA in general in Streptomyces species.
Umeyama
T
T
Department of Biotechnology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.
Naruoka
A
A
Horinouchi
S
S
D000595:Amino Acid Sequence; D002455:Cell Division / Q000235:genetics; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000494:pharmacology; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013302:Streptomyces / Q000201:enzymology / Q000235:genetics* / Q000648:ultrastructure; D013379:Substrate Specificity; D013696:Temperature
D004791:Enzyme Inhibitors; D008670:Metals; D010749:Phosphoprotein Phosphatases