The temporal regulation of protein synthesis during synchronous bud or mycelium formation in the dimorphic yeast Candida albicans☆

[摘要] WhenstationaryphasecellsofthedimorphicyeastCandidaalbicansaredilutedintofreshmediumat37°CateitherpH4.5orpH6.5,theyevaginateatexactlythesametimeandwiththesamesynchrony.However,theythengrowinthebuddingyeastformattheformerpHandintheelongatemyceliumformatthelatterpH.Threephasesofproteinsynthesisaredistinguishedforcellsformingeitherbudsormycelia:aninitial50-minperiod(phaseI)duringwhichtotalcellproteinremainsconstantandtherateofincorporationoflabeledaminoacidintoproteinisvirtuallyzero;asecondperiod(phaseII)duringwhichthereisaslowbutconstantincreaseinbothtotalcellproteinandtherateofincorporation;andathirdperiod(phaseIII)duringwhichthereisadramaticincreaseinbothtotalcellproteinandtherateofincorporation.ThetransitionfromphaseItophaseIIoccursatthesametimeforcellsformingeitherbudsormycelia,butthetransitionfromphaseIItophaseIIIoccurs20to30minlaterinthemyceliumthaninthebudformingpopulation,thesametemporaldifferenceobservedforphenotypiccommitment.ThepolypeptidessynthesizedduringphasesIIandIIIwerefirstanalyzedbyone-dimensionalpolyacrylamidegelelectrophoresis.Thepatternsaresimilarforthetwophenotypes.ThemajorpolypeptidessynthesizedduringphaseIIarealsosynthesizedduringphaseIII,butinaddition,agroupofatleastfournewmajorpolypeptidesappearduringphaseIIIforbothphenotypes.TheminorpolypeptidessynthesizedduringphaseIIIwerealsocomparedbetweenthetwophenotypesbytwo-dimensionalpolyacrylamidegelelectrophoresis.Thepatterns,includingroughly200distinguishablepolypeptides,weresimilar.ThesimilaritiesinthepatternsofproteinsynthesisandthedelayintheonsetofphaseIIIinmyceliumformingcellsarediscussedintermsofphenotypiccommitment.Fromtheseconsiderations,alternatehypothesesfortheregulationoffungaldimorphism,inparticular,andcelldivergence,ingeneral,areproposed.

[学科分类] 生物科学（综合）