Purification and Comparison of Phosphoglycerate Kinases from Nitrifying Bacteria

概要

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Phosphoglycerate kinases[PGK, EC2.7.2.3]were purified as electrophoretically homogeneous proteins from four nitrifying bacteria: Nitrosomonas europaea ATCC 25978T(Ns), Nitrosomonas sp. TNO632(TNO), Nitrosomonas sp. K1(K1), Nitrobacter winogradskyi IFO 14297(Nb)and nonsulfur bacterium Rhodo-pseudomonas palustris JCM2524(Rp). The enzymes were all monomers with molecular masses of 44.6, 44.3, 43.7, 46.1, and 43.4 kDa, respectively. Ns-PGK and Nb-PGK had the same pH-activity curves with an optimum pH range of 8.0-8.5. The enzymes were stable in the pH range 7.0-9.0 when kept at 4℃ for 48 h. The temperature optima of Ns-PGK and Nb-PGK were 50 and 40℃, respectively. Both enzymes were strongly inhibited by pCMB and SDS at 1 mM, ATP was effective, while other nucleotides did not serve as a phosphate donor. The N-terminal amino acid sequences of Ns-PGK and Nb-PGK were maximally homologous(90-95%)with TNO-PGK and Rp-PGK, respectively. However, the degree of PGK homology was as low as 45-59% between the two nitrifying bacteria genera. As previously observed, all Nitrosomonas and Nitrobacter strains constitute a monophyletic assemblage within the beta and alpha subdivisions of the proteobacteria, respectively. The differences in the N-terminal amino acid sequences of the PGKs coincided with the taxonomic differences of the bacterial genera according to the molecular phylogenetic tree.
社団法人日本生物工学会の論文
1998-10-25