A new protein carrying an NmrA-like domain is required for cell differentiation and development in Dictyostelium discoideum

摘要

WehaveisolatedaemDictyostelium/emmutantunabletoinduceexpressionoftheprestalk-specificmarkeremecmB/eminmonolayerassays.Thedisruptedgene,empadA/em,leadstoarangeofphenotypicdefectsingrowthanddevelopment.WeshowthatempadA/emisessentialforgrowth,andwehavegeneratedathermosensitivemutantallele,empadAsupminus;/sup/em.Atthepermissivetemperature,mutantcellsgrowpoorly;theyremainlongerattheslugstageduringdevelopmentandaredefectiveinterminaldifferentiation.Attherestrictivetemperature,growthiscompletelyblocked,whiledevelopmentispermanentlyarrestedpriortoculmination.empadAsupminus;/sup/emslugsaredeficientinprestalkAcelldifferentiationandpresentanabnormalemecmB/emexpressionpattern.Sequencecomparisonsandpredictedthree-dimensionalstructureanalysesshowthatPadAcarriesanNmrA-likedomain.NmrAisanegativetranscriptionalregulatorinvolvedinnitrogenmetaboliterepressioninemAspergillusnidulans/em.PadApredictedstructureshowsaNAD(P)sup+/sup-bindingdomain,whichwedemonstratethatisessentialforfunction.WeshowthatempadAsupminus;/sup/emdevelopmentismoresensitivetoammoniathanwild-typecellsandtwoammoniumtransporters,emamtA/emandemamtC/em,appearderepressedduringempadAsupminus;/sup/emdevelopment.OurdatasuggestthatPadAbelongstoanewfamilyofNAD(P)sup+/sup-bindingproteinsthatlinkmetabolicchangestogeneexpressionandisrequiredforgrowthandnormaldevelopment./p/div