The spore coat of a fucosylation mutant in Dictyostelium discoideum☆

摘要

StrainHL250ofDictyosteliumdiscoideumcannotconvertGDP-mannosetoGDP-fucose,resultinginaninabilitytofucosylateprotein.Thisaffectsagroupofproteinswhicharenormallyfucosylatedintracellularlyandthensecretedviapresporevesiclestobecomepartoftheouterlaminaofthesporecoat.WehavefoundthatstrainHL250neverthelessaccumulatestypicalamountsoftheseproteins,storesthemnormallyinpresporevesicles,andsecretesthemnormallytobecomeapartofthesporecoat.However,affectedproteinsareproteolyzedaftergermination,thesporecoatismoreaccessibletopenetrationbyamacromolecularprobe,andgerminationisinefficientinolderspores.Thesefindingscanbeexplainedbyadependenceoftheintegrityoftheouterlayerofthesporecoatonprotein-linkedfucose.