ISOLATION AND CHARACTERIZATION OF THE MAJOR FORM OF POLYPRENYL-PHOSPHO-MANNOSE FROM MYCOBACTERIUM-SMEGMATIS

We isolated from the endogenous polyprenyl-phospho-sugar pool of Mycob acterium smegmatis two mannose-containing compounds, i,e,, a partially saturated C-35-octahydroheptaprenyl-P-mannose and a fully unsaturated C-50-decaprenyl-P-mannose. The relative amount of C-35-polyprenyl-P-m annose in mycobacterial cells was comparable to that of decaprenyl-P-p entoses and, at least, an order of magnitude higher than that of C-50- decaprenyl-P-mannose. The major form of mycobacterial polyprenyl-P-man nose was structurally characterized by combined gas chromatography-mas s spectrometry, fast-atom bombardment tandem mass spectrometry and pro ton-nuclear magnetic resonance spectroscopy as nopyranosyl-monophospho -(C-35)octahydroheptaprenol of which all three isoprene units have Z ( cis) configuration. The differences in the structure and cellular conc entrations of the mycobacterial mannosyl-P-polyprenols reflect distinc t biochemical pathways of the two compounds and suggest the existence of specific GDP-Man:polyprenyl-P mannosyltransferases (synthetases) ab le to distinguish between C-35-octahydroheptaprenyl- and C-50-decapren yl- phosphates of mycobacteria, Since the 6'-O-mycoloylated form of C- 35-octahydroheptaprenyl-P-mannose isolated from M, smegmatis is appare ntly involved in mycolate rather than mannosyl transfer reactions, we speculate that a catabolic pathway responsible for degradation of C-35 -P-mannose and recycling C-35-octahydroheptaprenyl phosphate might exi st in mycobacteria.