The Escherichia coli MotAB proton channel unplugged

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dc.contributor.authorHosking, Edan R.
dc.contributor.authorVogt, Christian
dc.contributor.authorBakker, Evert P.
dc.contributor.authorManson, Michael D.
dc.date.accessioned2021-12-23T16:13:17Z-
dc.date.available2021-12-23T16:13:17Z-
dc.date.issued2006
dc.identifier.issn00222836
dc.identifier.urihttps://osnascholar.ub.uni-osnabrueck.de/handle/unios/10488-
dc.description.abstractThe MotA and MotB proteins of Escherichia coli serve two functions. The MotA(4)MOtB(2) complex attaches to the cell wall via MotB to form the stator of the flagellar motor. The complex also couples the flow of hydrogen ions across the cell membrane to movement of the rotor. The TM3 and TM4 transmembrane helices of MotA and the single TM of MotB comprise the proton channel, which is inactive until the complex assembles into a motor. Here, we identify a segment of the MotB protein that acts as a plug to prevent premature proton flow. The plug is in the periplasm just C-terminal to the MotB TM. It consists of an amphipathic alpha helix flanked by Pro52 and Pro65. When MotA is over-expressed with MotB deleted for residues 51-70, a massive influx of protons acidifies the cytoplasm without significantly depleting the proton motive force. Either that acidification or some sequela thereof, such as potassium or water efflux from the cells, inhibits growth. The Pro residues and Ile58, Tyr61, and Phe62 are essential for plug function. Cys-substituted MotB proteins form a disulfide bond between the two plugs that hold the channels open, and the plugs function in trans within the MotA(4)MotB(2) complex. We present a model in which the MotA(4)MOtB(2) complex forms in the bulk membrane. Before association with a motor, we propose the plugs insert into the cell membrane parallel with its periplasmic face and interfere with channel formation. When a complex incorporates into a motor, the plugs leave the membrane and associate with each other via their hydrophobic faces to hold the proton channel open. (c) 2006 Elsevier Ltd. All rights reserved.
dc.language.isoen
dc.publisherACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
dc.relation.ispartofJOURNAL OF MOLECULAR BIOLOGY
dc.subjectBACTERIAL FLAGELLAR MOTORS
dc.subjectBASAL BODY
dc.subjectBiochemistry & Molecular Biology
dc.subjectchannel gating
dc.subjectCOMPONENTS
dc.subjectflagellar motor
dc.subjectGENE-EXPRESSION
dc.subjectGROWING-CELLS
dc.subjectmembrane proteins
dc.subjectMEMBRANE TOPOLOGY
dc.subjectmotility
dc.subjectPROTEIN
dc.subjectproton channel
dc.subjectRESIDUES
dc.subjectROTATION
dc.subjectTORQUE-GENERATING UNITS
dc.titleThe Escherichia coli MotAB proton channel unplugged
dc.typejournal article
dc.identifier.doi10.1016/j.jmb.2006.09.035
dc.identifier.isiISI:000242769200006
dc.description.volume364
dc.description.issue5
dc.description.startpage921
dc.description.endpage937
dc.identifier.eissn10898638
dc.publisher.place24-28 OVAL RD, LONDON NW1 7DX, ENGLAND
dcterms.isPartOf.abbreviationJ. Mol. Biol.
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