title: Mutations alter the sodium versus proton use of a Bacillus clausii flagellar motor and confer dual ion use on Bacillus subtilis motors.
abstract: Bacterial flagella contain membrane-embedded stators, Mot complexes, that harness the energy of either transmembrane proton or sodium ion gradients to power motility. Use of sodium ion gradients is associated with elevated pH and sodium concentrations. The Mot complexes studied to date contain channels that use either protons or sodium ions, with some bacteria having only one type and others having two distinct Mot types with different ion-coupling. Here, alkaliphilic Bacillus clausii KSM-K16 was shown to be motile in a pH range from 7 to 11 although its genome encodes only one Mot (BCl-MotAB). Assays of swimming as a function of pH, sodium concentration, and ion-selective motility inhibitors showed that BCl-MotAB couples motility to sodium at the high end of its pH range but uses protons at lower pH. This pattern was confirmed in swimming assays of a statorless Bacillus subtilis mutant expressing either BCl-MotAB or one of the two B. subtilis stators, sodium-coupled Bs-MotPS or proton-coupled Bs-MotAB. Pairs of mutations in BCl-MotB were identified that converted the naturally bifunctional BCl-MotAB to stators that preferentially use either protons or sodium ions across the full pH range. We then identified trios of mutations that added a capacity for dual-ion coupling on the distinct B. subtilis Bs-MotAB and Bs-MotPS motors. Determinants that alter the specificity of bifunctional and single-coupled flagellar stators add to insights from studies of other ion-translocating transporters that use both protons and sodium ions.
authors.affiliation: Graduate School of Life Sciences and Bio-Nano Electronics Research Center, Toyo University, Oura-gun, Gunma 374-0193, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Terahara
authors.forename: Terry A
authors.initials: TA
authors.lastname: Krulwich
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ito
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D001407:Bacillus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001412:Bacillus subtilis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D005407:Flagella / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000378:metabolism; D020409:Molecular Motor Proteins / Q000235:genetics / Q000378:metabolism*; D009068:Movement / Q000187:drug effects / Q000502:physiology; D009154:Mutation; D011522:Protons; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D007477:Ions; D020409:Molecular Motor Proteins; C063010:MotA protein, Bacteria; C064779:MotB protein, Bacteria; D011522:Protons; D014475:Uncoupling Agents; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000584:Amiloride; D012964:Sodium; C039614:ethylisopropylamiloride
references.citation: J Bacteriol. 2005 Feb;187(4):1207-9
references.pmid: 15687183
references.citation: J Bacteriol. 1996 Aug;178(16):5024-6
references.pmid: 8759871
references.citation: Mol Microbiol. 2004 Aug;53(4):1035-49
references.pmid: 15306009
references.citation: Extremophiles. 2007 Jul;11(4):597-603
references.pmid: 17429572
references.citation: Appl Microbiol Biotechnol. 1995 Jul;43(3):473-81
references.pmid: 7632397
references.citation: Methods Mol Biol. 1997;67:141-9
references.pmid: 9031138
references.citation: Science. 2005 Apr 29;308(5722):659-62
references.pmid: 15860619
references.citation: J Bacteriol. 1995 Sep;177(17):5158-60
references.pmid: 7665498
references.citation: Arch Microbiol. 2007 Mar;187(3):239-47
references.pmid: 17165029
references.citation: FEBS Lett. 2001 Apr 13;494(3):157-60
references.pmid: 11311232
references.citation: EMBO J. 2000 Jul 17;19(14):3639-48
references.pmid: 10899118
references.citation: J Bacteriol. 2006 Apr;188(7):2701-5
references.pmid: 16547058
references.citation: Nature. 1994 Oct 27;371(6500):752
references.pmid: 7935835
references.citation: Mol Microbiol. 1995 Feb;15(3):592
references.pmid: 7783630
references.citation: Annu Rev Biochem. 2003;72:19-54
references.pmid: 12500982
references.citation: J Biol Chem. 1983 Sep 10;258(17):10577-81
references.pmid: 6885795
references.citation: Biosci Biotechnol Biochem. 1992 Jan;56(1):48-53
references.pmid: 1368134
references.citation: Int Rev Cytol. 2004;233:93-134
references.pmid: 15037363
references.citation: J Bacteriol. 1998 Jul;180(13):3312-6
references.pmid: 9642181
references.citation: J Mol Biol. 2005 Sep 16;352(2):396-408
references.pmid: 16095621
references.citation: Science. 2005 Apr 29;308(5722):654-9
references.pmid: 15802565
references.citation: Appl Environ Microbiol. 2001 Feb;67(2):834-9
references.pmid: 11157251
references.citation: Mol Microbiol. 1994 Apr;12(2):333-4
references.pmid: 8057857