Biosynthesis of glycoproteins in the pathogenic fungus Candida albicans: Activation of dolichol phosphate mannose synthase by cAMP-mediated protein phosphorylation

Abstract

Following incubation with ATP and a cAMP-dependent protein kinase under optimal conditions of lipid acceptor, phospholipid and metal ion requirements, the transfer activity of partially purified dolichol phosphate mannose synthase (DPMS) increased about 60% and this activation correlated with a 50% increase in V_max with no alteration in the apparent K_m for GDP-Manose. Phosphorylation with [γ-³²P]ATP resulted in the labeling of several polypeptides, one of which exhibited the molecular weight of the enzyme (30 kDa) and was also recognized using a specific anti-DPMS monoclonal antibody. This and the fact that the phosphate label could be removed by an alkaline phosphatase indicate that Candida DPMS may be regulated by phosphorylation–dephosphorylation, a mechanism that has been proposed for the enzyme in other organisms.