Ammonium transporter C of Dictyostelium discoideum is required for correct prestalk gene expression and for regulating the choice between slug migration and culmination

摘要

AmmoniumtransporterC(AmtC)isoneofthreetransportersinemDictyostelium/emthathavebeenproposedtoregulateentryandexitofammoniainacelltypedependentmannerandtomediateammoniasignaling.PreviousworkdemonstratedthatdisruptionoftheemamtC/emgeneresultsinasluggerphenotypeinwhichthecellsremainasmigratingslugswhentheyshouldformfruitingbodies.Moredetailedstudiesonthenullstrainrevealedthatdifferentiationofprestalkcelltypeswasdelayedandmaintenanceofprestalkcellgeneexpressionwasdefective.TherewaslittleornoexpressionofemecmB/em,amarkerfortheinitiationofculmination.NormalexpressionofCudA,anuclearproteinrequiredforculmination,wasabsentintheanteriorprestalkzone.TheabsenceofCudAwithinthetipregionwasattributabletothelackofnuclearlocalizationofthetranscriptionfactorSTATa,despiteexpressionofadenylylcyclaseAmRNAintheslugtips.DisruptionofthehistidinekinasegeneemdhkC/emintheemamtC/emnullstrainrestoredSTATaandCudAexpressionandtheabilitytoculminate.TheresultssuggestthatthelackofnucleartranslocationofSTATaresultsfromlowcAMPduetoamisregulatedandoveractiveDhkCphosphorelayintheemamtC/emnullstrain./p/div