The adenosine 5'-triphosphate(ATP)-binding cassette(ABC)transporter,IrtAB,plays a vital role in the replication and viability of Mycobacterium tuberculosis(Mtb),where its function is to import iron-loaded sideroph...The adenosine 5'-triphosphate(ATP)-binding cassette(ABC)transporter,IrtAB,plays a vital role in the replication and viability of Mycobacterium tuberculosis(Mtb),where its function is to import iron-loaded siderophores.Unusually,it adopts the canonical type IV exporter fold.Herein,we report the structure of unliganded Mtb IrtAB and its structure in complex with ATP,ADP,or ATP analogue(AMP-PNP)at resolutions ranging from 2.8 to 3.5Å.The structure of IrtAB bound ATP-Mg2+shows a“head-to-tail”dimer of nucleotide-binding domains(NBDs),a closed amphipathic cavity within the transmembrane domains(TMDs),and a metal ion liganded to three histidine residues of IrtA in the cavity.Cryo-electron microscopy(Cryo-EM)structures and ATP hydrolysis assays show that the NBD of IrtA has a higher affinity for nucleotides and increased ATPase activity compared with IrtB.Moreover,the metal ion located in the TM region of IrtA is critical for the stabilization of the conformation of IrtAB during the transport cycle.This study provides a structural basis to explain the ATP-driven conformational changes that occur in IrtAB.展开更多
基金supported by grants from the National Key Research and Development Program of China(Grant No.2022YFC2302900)the National Natural Science Foundation of China(Grant No.32171217 to B.Z.)+5 种基金Shanghai Sailing Program(Grant No.21YF1429700 to B.Z.)Young Elite Scientists Sponsorship Program by CAST(Grant No.2021QNRC001)the Lingang Laboratory(Grant No.LG202101-01-08)Shanghai Municipal Science and Technology Major Project(Grant No.ZD2021CY001)Science and Technology Commission of Shanghai Municipality(Grant No.20XD1422900 to H.Y.)the Shanghai Frontiers Science Center for Biomacromolecules and Precision Medicine,Shanghaitech University.
文摘The adenosine 5'-triphosphate(ATP)-binding cassette(ABC)transporter,IrtAB,plays a vital role in the replication and viability of Mycobacterium tuberculosis(Mtb),where its function is to import iron-loaded siderophores.Unusually,it adopts the canonical type IV exporter fold.Herein,we report the structure of unliganded Mtb IrtAB and its structure in complex with ATP,ADP,or ATP analogue(AMP-PNP)at resolutions ranging from 2.8 to 3.5Å.The structure of IrtAB bound ATP-Mg2+shows a“head-to-tail”dimer of nucleotide-binding domains(NBDs),a closed amphipathic cavity within the transmembrane domains(TMDs),and a metal ion liganded to three histidine residues of IrtA in the cavity.Cryo-electron microscopy(Cryo-EM)structures and ATP hydrolysis assays show that the NBD of IrtA has a higher affinity for nucleotides and increased ATPase activity compared with IrtB.Moreover,the metal ion located in the TM region of IrtA is critical for the stabilization of the conformation of IrtAB during the transport cycle.This study provides a structural basis to explain the ATP-driven conformational changes that occur in IrtAB.
