The third chemotaxis locus of Rhodobacter sphaeroides is essential for chemotaxis

Mol Microbiol. 2002 Nov;46(4):1081-94. doi: 10.1046/j.1365-2958.2002.03218.x.


The purple photosynthetic bacterium Rhodobacter sphaeroides has three loci encoding multiple homologues of the bacterial chemosensory proteins: 13 putative chemoreceptors, four CheW, four CheA, six CheY, two CheB and three CheR. Previously, studies have shown that, although deletion of cheOp1 led to only minor changes in behaviour, deletion of cheOp2 led to a loss of taxis. The third locus encodes two CheA, one CheR, one CheB, one CheW, one CheY, a putative cytoplasmic chemoreceptor (TlpT) and a protein showing homology to the chromosomal partitioning factor Soj (designated Slp). Here, we show that every protein encoded by this locus is essential for normal chemotaxis. Phototaxis is also dependent upon all the components of this locus, except CheB2 and Slp. The two putative CheA proteins encoded in this locus are unusual. CheA3 has only the P1 domain and the P5 regulatory domain linked by a large internal domain, whereas CheA4 lacks the P1 and P2 domains required for phosphorylation and response regulator binding. These data indicate that the minimal set of proteins required for normal chemotaxis in R. sphaeroides is all the proteins encoded by cheOp2 and the third chemotaxis locus, and that the multiple chemosensory protein homologues found in R. sphaeroides are not redundant.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Chemotaxis / genetics*
  • Escherichia coli / genetics
  • Escherichia coli Proteins*
  • Histidine Kinase
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Methyl-Accepting Chemotaxis Proteins
  • Methyltransferases / genetics
  • Methyltransferases / metabolism
  • Molecular Sequence Data
  • Multigene Family
  • Rhodobacter sphaeroides / cytology
  • Rhodobacter sphaeroides / genetics*
  • Rhodobacter sphaeroides / physiology
  • Sequence Deletion
  • Sequence Homology, Amino Acid


  • Bacterial Proteins
  • CheW protein, E coli
  • Escherichia coli Proteins
  • Membrane Proteins
  • Methyl-Accepting Chemotaxis Proteins
  • cheY protein, E coli
  • CheW protein, Bacteria
  • CheB protein, Bacteria
  • Methyltransferases
  • chemotaxis methyltransferase
  • Histidine Kinase
  • cheA protein, E coli