Polyprenol phosphate as an acceptor of mannose from guanosine diphosphate mannose in Aspergillus niger

摘要

pGrowth of iAspergillus niger/i in the presence of [2-sup14/supC]mevalonate and sup32/supPsubi/sub led to the formation of a lipid, containing sup14/supC (0.14% of dose) and sup32/supP (0.009% of dose), that had chromatographic properties identical with those of iexo/i-methylene-hexahydropolyprenol phosphate. When a particulate enzyme preparation from the thallus of iA. niger/i was incubated with GDP-[sup14/supC]mannose, the main radioactive products were mannose 1-phosphate (57% of products) and mannose (18%). In addition radioactive mannan (8%) and a mannolipid (2%) were formed. The latter was identified as iexo/i-methylene-hexahydropolyprenol phosphate mannose on the basis of its chromatographic properties, acid lability and on the increase in formation of the mannolipid when the phosphate of iexo/i-methylene-hexahydropolyprenols was added to the incubation mixture. The phosphates of ficaprenols and cetyl alcohol caused no corresponding increase. These observations are interpreted as evidence that the thallus of iA. niger/i contains a mannose transferase that uses the phosphate of iexo/i-methylene-hexahydropolyprenols as an acceptor. This situation is discussed in the light of the analogous involvement of a prenol phosphate mannose as an intermediate in the biosynthesis of bacterial wall mannan./p