tailieunhanh - Báo cáo khoa học: Two dNTP triphosphohydrolases from Pseudomonas aeruginosa possess diverse substrate specificities

Nucleotide hydrolases are known to hydrolyze not only noncanonical dNTPs to reduce the risk of mutation, but also canonical dNTPs to main-tain the dNTP concentrations in the cell. dGTP triphosphohydrolase from Escherichia coliis known as an enzyme that hydrolyzes dGTP. | Two dNTP triphosphohydrolases from Pseudomonas aeruginosa possess diverse substrate specificities Ryosuke Mega1 Naoyuki Kondo Noriko Nakagawa2 3 Seiki Kuramitsu1 2 3 and Ryoji Masui2 3 1 Graduate Schoolof Frontier BiologicalSciences Osaka University Osaka Japan 2 Department of BiologicalSciences Graduate Schoolof Sciences Osaka University Osaka Japan 3 RIKEN SPring-8 Center Hyogo Japan Keywords dGTP triphosphohydrolase enzyme assay HD superfamily Pseudomonas aeruginosa substrate specificity Correspondence R. Masui Department of Biological Sciences Graduate School of Sciences Osaka University 1-1 Machikaneyama-cho Toyonaka Osaka 560-0043 Japan Fax 81 6 6850 5442 Tel 81 6 6850 5434 E-mail rmasui@ Present address Research Center for Asian Infectious Diseases Institute of MedicalScience University of Tokyo Japan Received 19 November 2008 revised 20 February 2009 accepted 1 April 2009 doi Nucleotide hydrolases are known to hydrolyze not only noncanonical dNTPs to reduce the risk of mutation but also canonical dNTPs to maintain the dNTP concentrations in the cell. dGTP triphosphohydrolase from Escherichia coli is known as an enzyme that hydrolyzes dGTP. Recently we identified a triphosphohydrolase from Thermus thermophilus HB8 that hydrolyzes all canonical dNTPs through a complex activation mechanism. These dNTP triphosphohydrolases are widely distributed in eubacteria but it is difficult to predict whether they possess hydrolytic activity for dGTP or dNTP. To obtain information concerning the structure-function relationships of this protein family we characterized two dNTP triphosphohydrolases PA1124 and PA3043 from Pseudomonas aeruginosa. Molecular phylogenic analysis showed that dNTP triphosphohydrolases can be classified into three groups. Experimentally PA1124 had a preference for dGTP similar to the E. coli enzyme whereas PA3043 displayed a broad substrate specificity. Both enzymes hydrolyzed substrates in the .