The conserved Lys-95 charged residue cluster is critical for the homodimerization and enzyme activity of human ribonucleotide reductase small subunit M2.

ABSTRACT: Ribonucleotide reductase (RR) catalyzes the reduction of ribonucleotides to deoxyribonucleotides for DNA synthesis. Human RR small subunit M2 exists in a homodimer form. However, the importance of the dimer form to the enzyme and the related mechanism remain unclear. In this study, we tried to identify the interfacial residues that may mediate the assembly of M2 homodimer by computational alanine scanning based on the x-ray crystal structure. Co-immunoprecipitation, size exclusion chromatography, and RR activity assays showed that the K95E mutation in M2 resulted in dimer disassembly and enzyme activity inhibition. In comparison, the charge-exchanging double mutation of K95E and E98K recovered the dimerization and activity. Structural comparisons suggested that a conserved cluster of charg

SUBMITTER: Chen X 

PROVIDER: S-EPMC3887214 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature