Motility protein A, also known as MotA Pait, is a bacterial protein that is encoded by the motA gene. It is a component of the flagellar motor.[1] More specifically, MotA and MotB make the stator of a H+ driven bacterial flagellum and surround the rotor as a ring of about 8–10 particles. MotA and MotB are integral membrane proteins.[2] MotA has four transmembrane domains.

Motility protein A
OrganismEscherichia coli str. K-12
Alt. symbolsECK1891; flaJ; JW1879
RefSeq (Prot)NP_416404.1
Other data
Chromosomechromosome: 1.97 - 1.98 Mb

Both proteins are part of the H+ channel that makes possible the flux of protons and the motor's rotation.

In MotA mutants, the motor function is reestablished if the MotA protein is expressed.

Though MotA and MotB are part of the proteins required for H+ mediated flagellar motility, they show a high degree of homology to the PomA and PomB proteins present in bacterial species utilizing Na+ ion fluxes to power flagella and studies have revealed that a 'pomA' mutant of Vibrio alginolyticus can regain motility by expression of MotA.[3] As restoring motility of pomA mutants by heterologous expression of MotA does not change the ion used to power the flagellum of the transgenic Vibrio alginolyticus, MotA is not in itself an essential specificity factor in ion selectivity,[3] though that does not exclude it being partially involved in determining ion specificity of the flagellar complex.

See alsoEdit


  1. ^ Blair DF, Berg HC (February 1990). "The MotA protein of E. coli is a proton-conducting component of the flagellar motor". Cell. 60 (3): 439–49. doi:10.1016/0092-8674(90)90595-6. PMID 2154333.
  2. ^ Stolz B, Berg HC (November 1991). "Evidence for interactions between MotA and MotB, torque-generating elements of the flagellar motor of Escherichia coli". J. Bacteriol. 173 (21): 7033–7. PMC 209062. PMID 1938906.
  3. ^ a b Asai Y, Kawagishi I, Sockett RE, Homma M (October 1999). "Hybrid motor with H(+)- and Na(+)-driven components can rotate Vibrio polar flagella by using sodium ions". J. Bacteriol. 181 (20): 6332–8. PMC 103767. PMID 10515922.

Further readingEdit

  • Eisenbach M, Lengeler JW, Varon M; D. Gutnick D; Firtel FA, Omann GM, Tamada A, Murakami F (2004). Chemotaxis. River Edge, N.J: Imperial College Press. ISBN 1-86094-413-2.CS1 maint: multiple names: authors list (link)
  • Stackebrandt, Erko; Dworkin, Martin; Falkow, Stanley; Rosenberg, Eugene; Karl-Heinz Schleifer (2006). The prokaryotes: a handbook on the biology of bacteria. Berlin: Springer. ISBN 0-387-25476-5.