A phosphate-stimulated NAD(P)⁺-dependent glyceraldehyde-3-phosphate dehydrogenase in<i>Bacillus cereus</i>

Abstract

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a key enzyme of central carbon metabolism, was studied in a Bacillus cereus strain isolated from the phosphate layer from Morocco. Enzymatic assays with cell extracts demonstrated that when grown on Luria-Bertani (LB) medium, B. cereus contains a major NAD+-dependent GAPDH activity and only traces of NADP+-dependent activity, but in cells grown on Pi-supplemented LB medium a strong increase of the NADP+-dependent activity, that became predominant, occurs concurrently with a GAPDH protein increase. Our results show that B. cereus possesses two GAPDH activities, namely NAD+- and NADP+-dependent, catalyzed by two enzymes with distinct coenzyme specificity and different phosphate regulation patterns. The finding of a phosphate-stimulated NADP+-dependent GAPDH in B. cereus indicates that this bacterium can modulate its primary carbon metabolism according to phosphate availability.