The nucleoside diphosphate kinase of Mycobacterium smegmatis: identification of proteins that modulate specificity of nucleoside triphosphate synthesis by the enzyme

Molecular Microbiology
S ShankarA M Chakrabarty

Abstract

We report the purification and characterization of the enzyme nucleoside diphosphate kinase (Ndk) from Mycobacterium smegmatis. The N-terminus of the enzyme was blocked but an internal sequence showed approx. 70% homology with the same enzymes from Pseudomonas aeruginosa and Escherichia coli. immobilization of the mycobacterial nucleoside diphosphate kinase on a Sepharose 4 B matrix and passing the total cell extract through it revealed four proteins (P70, P65, P60, and P50, respectively) of M(r) 70 kDa, 65 kDa, 60 kDa and 50 kDa that were retained by the column. While the proteins of M(r) 70 kDa and 50 kDa modulated the activity of Ndk directing it towards GTP synthesis, the 60 kDa protein channelled the specificity of Ndk entirely towards CTP synthesis. The 65 kDa protein modulated the specificity of Ndk directing it entirely towards UTP synthesis. The specificity for such mycobacterial proteins towards NTP synthesis is retained when they are complexed with P. aeruginosa Ndk. We further demonstrate that the P70 protein is pyruvate kinase and that each of the four proteins forms a complex with Ndk and alters its substrate specificity. Given the ubiquitous nature of Ndk in the living cell and its role in maintaining correct rat...Continue Reading

Citations

Feb 14, 2009·Purinergic Signalling·Robson Coutinho-SilvaDavid M Ojcius
Mar 6, 1999·Current Opinion in Microbiology·I Cases, V de Lorenzo
Feb 13, 2003·European Journal of Biochemistry·Puneet ChopraYogendra Singh
Jan 16, 2010·The Journal of Biological Chemistry·Mohammad Rubayet HasanLacy Daniels
Feb 5, 2008·Molecular and Biochemical Parasitology·Bala Krishna KolliKwang-Poo Chang

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