L-xylulose-5-phosphate 3-epimerase (UlaE)

L-xylulose-5-phosphate 3-epimerase (UlaE) is a bacterial enzyme that plays a critical role in the anaerobic metabolism of L-ascorbate (Vitamin C) [2, 9]. It catalyzes the reversible epimerization of L-xylulose 5-phosphate to L-ribulose 5-phosphate, a key step in the pathway that converts ascorbate-derived carbons into intermediates for the pentose phosphate pathway [11, 18]. This enzyme is primarily found in enteric bacteria, including Escherichia coli, Klebsiella pneumoniae, and Streptococcus mutans, where it is encoded by the ula (or sga) operon [13, 15, 19]. By enabling the utilization of ascorbate as an alternative carbon and energy source, UlaE contributes to bacterial survival and fitness within the anaerobic environment of the host gastrointestinal tract [18, 33]. Since humans lack this specific L-sugar epimerase, it is considered a potential target for the development of novel, narrow-spectrum antimicrobial agents [11, 12]. Structural analysis reveals that UlaE adopts a triosephosphate isomerase (TIM) barrel fold and utilizes a metal-dependent mechanism for catalysis [1, 6, 13]. Inhibition of this enzyme could disrupt bacterial energy production and reduce the virulence of pathogens that rely on ascorbate catabolism [12, 15]. Research into UlaE inhibitors is currently in the early stages, focusing on understanding its unique phosphate-binding motif and catalytic site to ensure selectivity over human metabolic enzymes [13, 21]. The enzyme's activity is essential for the metabolic flux that supports bacterial growth when primary carbon sources are limited [18]. Consequently, UlaE represents a promising candidate for therapeutic intervention in drug-resistant bacterial infections [12].

Other names

L-ribulose-5-phosphate 3-epimeraseSgaUulaEyjfWPentose-5-phosphate 3-epimerase

Inhibition of enzymatic activity to disrupt bacterial ascorbate metabolism.