Structure and function of the C‐terminal domain of MrpA in the Bacillus subtilis Mrp‐antiporter complex – The evolutionary progenitor of the long horizontal helix in complex I

摘要

MrpAandMrpDarehomologoustoNuoL,NuoMandNuoNincomplexIoverthefirst14transmembranehelices.Inthiswork,theC‐terminaldomainofMrpA,outsidethisconservedarea,wasinvestigated.ThetransmembraneorientationwasfoundtocorrespondtothatofNuoJincomplexI.WehavepreviouslydemonstratedthatthesubunitNuoKishomologoustoMrpC.ThefunctionoftheMrpAC‐terminuswastestedbyexpressioninapreviouslyusedBacillussubtilismodelsystem.AtneutralpH,thetruncatedMrpAstillworked,butatpH8.4,whereMrp‐complexformationisneededforfunction,theC‐terminaldomainofMrpAwasabsolutelyrequired...