Structure of L-xylulose-5-Phosphate 3-epimerase (UlaE) from the anaerobic L-ascorbate utilization pathway of Escherichia coli: identification of a novel phosphate binding motif within a TIM barrel fold.

ABSTRACT: Three catabolic enzymes, UlaD, UlaE, and UlaF, are involved in a pathway leading to fermentation of l-ascorbate under anaerobic conditions. UlaD catalyzes a beta-keto acid decarboxylation reaction to produce L-xylulose-5-phosphate, which undergoes successive epimerization reactions with UlaE (L-xylulose-5-phosphate 3-epimerase) and UlaF (L-ribulose-5-phosphate 4-epimerase), yielding D-xylulose-5-phosphate, an intermediate in the pentose phosphate pathway. We describe here crystallographic studies of UlaE from Escherichia coli O157:H7 that complete the structural characterization of this pathway. UlaE has a triosephosphate isomerase (TIM) barrel fold and forms dimers. The active site is located at the C-terminal ends of the parallel beta-strands. The enzyme binds Zn(2+), which is coordinate

SUBMITTER: Shi R 

PROVIDER: S-EPMC2593225 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature