Sequence analyses of cyanobacterial bicarbonate transporters and their homologues

J Mol Microbiol Biotechnol. 2004;7(3):102-8. doi: 10.1159/000078653.


The primary HCO3- uptake system in the cyanobacterium Synecocystis is the Na+-dependent transporter SbtA. SbtA and its homologues were identified and shown to display a common topology of ten transmembrane segments (TMSs). These proved to have arisen by an intragenic duplication event from an ancestral gene encoding a five TMS protein product. A region of SbtA shows sufficient similarity to 10 TMS ABC-type integral membrane transport proteins to suggest a common origin. Phylogenetic analyses of the SbtA family revealed two clusters of cyanobacterial homologues with all non-cyanobacterial family members outside of these two clusters. The tree topology suggests that SbtA family members display multiple transport functions.

MeSH terms

  • Amino Acid Sequence
  • Bicarbonates / metabolism*
  • Biological Transport
  • Conserved Sequence
  • Cyanobacteria / genetics*
  • Cyanobacteria / metabolism
  • Gram-Negative Bacteria / metabolism
  • Gram-Positive Bacteria / metabolism
  • Molecular Sequence Data
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Sodium-Bicarbonate Symporters / chemistry
  • Sodium-Bicarbonate Symporters / genetics*
  • Sodium-Bicarbonate Symporters / metabolism


  • Bicarbonates
  • Sodium-Bicarbonate Symporters