On the reduction steps in the mevalonate independent 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway for isoprenoid biosynthesis in the bacterium Zymomonas mobilis

Zymomonas mobilis synthesizes triterpenoids of the hopane series via the me thylerythritol phosphate (MEP) pathway. Owing to the peculiar metabolic pat hways in this bacterium, [1-H-2]glucose is the appropriate substrate for ge nerating in vivo deuterium labeled NADP(2)H. After feeding of Z. mobilis wi th [1-H-2]glucose, deuterium labeling was found on all carbon atoms derived from C-2 and C-4 of isopentenyl diphosphate. The deuterium at C-4 arose fr om the NADPH dependent reduction catalyzed by the reducto-isomerase convert ing I-deoxy-D-xylulose 5-phosphate into 2-C-methyl-D-erythritol 4-phosphate . The deuterium at C-2 resulted from an additional reduction at a yet undet ermined steps of the MEP biosynthetic pathway. (C) 1999 Published by Elsevi er Science Ltd. All rights reserved.