Acid phosphatases (EC 22.214.171.124) catalyze the hydrolysis of phosphate monoesters or transfer of phosphate groups between phosphoester and alcohols. The enzymes catalyze optimally at acidic conditions and LY2874455 are completely and structurally different from alkaline phosphatases (EC 126.96.36.199), which
work optimally at alkaline conditions [25–27]. Unlike the alkaline phosphatases, the acid phosphatases, do not utilize metal ions in their catalysis. They rather utilize histidine residue to form a phospho-histidine-enzyme intermediate which is essential for their catalysis. In contrast, alkaline phosphatases make use of a phospho-serine-enzyme intermediate for their catalysis and have a binuclear Zn (II) active site [26, 28]. Phosphatases are
important in the physiology of an organism as they GDC-0941 concentration function in many catalytic reactions relating to activation or deactivation of enzymes. Deficiencies in phosphate metabolism have been reported to be related to reduction of virulence in many bacterial species such as Listeria monocytogenes, Streptococcus pneumoniae, Vibrio cholerae, Proteus mirabilis and M. tuberculosis[29–34]. The fact that histidine acid phosphatases and cofactor dependent phosphoglycerate mutases share similar catalytic amino acid residues and mechanism of catalysis warrants their placement in the same superfamily . This often leads to some difficulties in predicting the function of an enzyme that belongs to the superfamily. Thus, biochemical characterization of purified enzymes learn more is necessary before the function of any member of histidine phosphatase superfamily can be ascertained. In this study, we report the first cloning, purification and characterization of M. tuberculosis Rv2135c. In addition, we cloned and characterized Rv0489. Its role as a cofactor dependent phosphoglycerate mutase was confirmed. Results The histidine phosphatase motif in Rv2135c Using
NCBI BLAST , a number of proteins with similar sequences to Rv2135c were identified. Some sequences, including Rv0489, were aligned using ClustalX2 with the results shown in Figure 1. Most of the similar sequences contain the histidine phosphatase motif of ‘RHG’ , which contributes to catalysis, at the N-terminal region. The motif becomes ‘RHA’ (at residue 7–9) in Rv2135c. This is similar to the motif found in phosphoglycerate mutase domain containing Decitabine protein of C. parvum (GAN CAD98474). Other conserved residues known to be involved in the catalysis of this superfamily from the analysis of others members are also present in Rv2135c. [4, 9, 36]. These include Arg57, Glu82, and a fully conserved His153 at the C-terminal region, Figure 1. Figure 1 Multiple alignment of amino acid sequences of some members of histidine phosphatase superfamily with Rv2135c. The alignment was done with ClustalX2 using the default parameters. The asterisks indicate fully conserved amino acid residues of the superfamily.