Role of the yiaR and yiaS genes of Escherichia coli in metabolism of endogenously formed L-xylulose

Genes yiaP and yiaR of the yiaKLMNOPQRS cluster of Escherichia coli are req uired for the metabolism of the endogenously formed L-xylulose, whereas yia S is required for this metabolism only in araD mutants. Like AraD, YiaS was shown to have L-ribulose-5-phosphate 4-epimerase activity. Similarity of Y iaR to several 3-epimerases suggested that this protein could catalyze the conversion of L-xylulose-5-phosphate into L-ribulose-5-phosphate, thus comp leting the pathway between L-xylulose and the general metabolism.