ZomB Is Essential for Flagellar Motor Reversals in Shewanella Putrefaciens and Vibrio Parahaemolyticus

Mol Microbiol. 2018 Sep;109(5):694-709. doi: 10.1111/mmi.14070. Epub 2018 Aug 1.


The ability of most bacterial flagellar motors to reverse the direction of rotation is crucial for efficient chemotaxis. In Escherichia coli, motor reversals are mediated by binding of phosphorylated chemotaxis protein CheY to components of the flagellar rotor, FliM and FliN, which induces a conformational switch of the flagellar C-ring. Here, we show that for Shewanella putrefaciens, Vibrio parahaemolyticus and likely a number of other species an additional transmembrane protein, ZomB, is critically required for motor reversals as mutants lacking ZomB exclusively exhibit straightforward swimming also upon full phosphorylation or overproduction of CheY. ZomB is recruited to the cell poles by and is destabilized in the absence of the polar landmark protein HubP. ZomB also co-localizes to and may thus interact with the flagellar motor. The ΔzomB phenotype was suppressed by mutations in the very C-terminal region of FliM. We propose that the flagellar motors of Shewanella, Vibrio and numerous other species harboring orthologs to ZomB are locked in counterclockwise rotation and may require interaction with ZomB to enable the conformational switch required for motor reversals. Regulation of ZomB activity or abundance may provide these species with an additional means to modulate chemotaxis efficiency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics
  • Bacterial Proteins / physiology*
  • Chemotaxis / genetics
  • Chemotaxis / physiology*
  • Flagella / genetics
  • Flagella / physiology*
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology*
  • Methyl-Accepting Chemotaxis Proteins / genetics
  • Methyl-Accepting Chemotaxis Proteins / metabolism
  • Microscopy, Fluorescence
  • Mutation
  • Plasmids
  • Sequence Alignment
  • Shewanella putrefaciens / genetics
  • Shewanella putrefaciens / physiology*
  • Vibrio parahaemolyticus / genetics
  • Vibrio parahaemolyticus / physiology*


  • Bacterial Proteins
  • Membrane Proteins
  • Methyl-Accepting Chemotaxis Proteins