Structure and molecular phylogeny of sasA genes in cyanobacteria: Insights into evolution of the prokaryotic circadian system

Volodymyr Dvornyk, Hong Wen Deng, Eviatar Nevo

Research output: Contribution to journalArticlepeer-review

Abstract

Cyanobacteria are the simplest organisms known to have a circadian system. In addition to the three well-studied kai genes, kaiA, kaiB, and kaiC, an important element of this system is a two-component sensory transduction histidine kinase sasA. Using publicly available data of complete prokaryotic genomes, we performed structural and phylogenetic analyses of the sasA genes. Results show that this gene has a triple-domain structure, and the domains are under different selective constraints. The sasA gene originated in cyanobacteria probably through the fusion of the ancestral kaiB gene with a double-domain, two-component sensory transduction histidine kinase. The results of the phylogenetic analyses suggest that sasA emerged before the kaiA gene, about 3,000-2,500 MYA, and has evolved in parallel with the evolution of the kaiBC cluster. The observed concordant patterns of the sasA and kaiBC evolution suggest that these genes might compose an ancient KaiBC-SasA-based circadian system, without the kaiA gene, and that such a system still exists in some unicellular cyanobacteria.

Original languageEnglish
Pages (from-to)1468-1476
Number of pages9
JournalMolecular Biology and Evolution
Volume21
Issue number8
DOIs
StatePublished - Aug 2004

Keywords

  • Circadian system
  • Cyanobacteria
  • Evolution
  • Prokaryotes
  • sasA

ASJC Scopus subject areas

  • Genetics
  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology

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