Characterization of three mycobacterial DinB (DNA polymerase IV) paralogs highlights DinB2 as naturally adept at ribonucleotide incorporation.

ABSTRACT: This study unveils Mycobacterium smegmatis DinB2 as the founder of a clade of Y-family DNA polymerase that is naturally adept at incorporating ribonucleotides by virtue of a leucine in lieu of a canonical aromatic steric gate. DinB2 efficiently scavenges limiting dNTP and rNTP substrates in the presence of manganese. DinB2's sugar selectivity factor, gauged by rates of manganese-dependent dNMP versus rNMP addition, is 2.7- to 3.8-fold. DinB2 embeds ribonucleotides during DNA synthesis when rCTP and dCTP are at equimolar concentration. DinB2 can incorporate at least 16 consecutive ribonucleotides. In magnesium, DinB2 has a 26- to 78-fold lower affinity for rNTPs than dNTPs, but only a 2.6- to 6-fold differential in rates of deoxy versus ribo addition (kpol). Two other M. smegmatis Y-family

SUBMITTER: Ordonez H 

PROVIDER: S-EPMC4176160 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature