Interactions at the 2 and 5 positions of 5-phosphoribosyl pyrophosphate are essential in Salmonella typhimurium quinolinate phosphoribosyltransferase.

ABSTRACT: Quinolinate phosphoribosyltransferase (QAPRTase, EC 2.4.2.19) catalyzes an unusual phosphoribosyl transfer that is linked to a decarboxylation reaction to form the NAD precursor nicotinate mononucleotide, carbon dioxide, and pyrophosphate from quinolinic acid (QA) and 5-phosphoribosyl 1-pyrophosphate (PRPP). Structural studies and sequence similarities with other PRTases have implicated Glu214, Asp235, Lys153, and Lys284 in contributing to catalysis through direct interaction with PRPP. The four residues were substituted by site-directed mutagenesis. A nadC deletant form of BL21DE3 was created to eliminate trace contamination by chromosomal QAPRTase. The mutant enzymes were readily purified and retained their dimeric aggregation state on gel filtration. Substitution of Lys153 with Ala resu

SUBMITTER: Bello Z 

PROVIDER: S-EPMC2891058 | biostudies-literature | 2010 Feb

REPOSITORIES: biostudies-literature