PROTOPLAST PLASMA-MEMBRANE GLYCOPROTEINS IN 2 SPECIES OF ENTOMOPHTHORALEAN FUNGI

The entomophthoralean fungi Entomophaga maimaiga and E. aulicae show h ost preferential infection in lepidopterous insects. These fungi grow as protoplasts within the haemocoel of the infected insect. We investi gated differences in protoplast plasma membrane glycoproteins. The pla sma membrane proteins from E. maimaiga and E. aulicae were isolated an d assessed for enrichment based on H+-translocating ATPases which show membrane specific pH optima and specific inhibition sensitivities. Of the glycoproteins tested for, major differences in the pattern, type and magnitude of mannose glycosylation were observed in plasma membran e proteins from the two fungi. E. maimaiga plasma membrane proteins sh owed greater levels of glycosylation with mannose in relative comparis on to plasma membrane proteins isolated from E. aulicae. In contrast t o the differences observed with mannose glycosylation, both fungi show ed a single molecular mass protein that was glycosylated with sialic a cid as well as with galactose beta(1-4) linked to N-acetyl-D-glucosami ne. Addition of tunicamycin to culture media reduced the level of mann ose glycosylation of plasma membrane proteins. The results are discuss ed with reference to alteration of plasma membrane glycoproteins aidin g in avoidance of insect immune responses.