Cyanobacterial Two-Component Proteins: Structure,Diversity, Distribution, andEvolution

Abstract

SUMMARY A survey of the already characterized and potential two-component protein sequences that exist in the nine complete and seven partially annotated cyanobacterial genome sequences available (as of May 2005) showed that the cyanobacteria possess a much larger repertoire of such proteins than most other bacteria. By analysis of the domain structure of the 1,171 potential histidine kinases, response regulators, and hybrid kinases, many various arrangements of about thirty different modules could be distinguished. The number of two-component proteins is related in part to genome size but also to the variety of physiological properties and ecophysiologies of the different strains. Groups of orthologues were defined, only a few of which have representatives with known physiological functions. Based on comparisons with the proposed phylogenetic relationships between the strains, the orthology groups show that (i) a few genes, some of them clustered on the genome, have been conserved by all species, suggesting their very ancient origin and an essential role for the corresponding proteins, and (ii) duplications, fusions, gene losses, insertions, and deletions, as well as domain shuffling, occurred during evolution, leading to the extant repertoire. These mechanisms are put in perspective with the different genetic properties that cyanobacteria have to achieve genome plasticity. This review is designed to serve as a basis for orienting further research aimed at defining the most ancient regulatory mechanisms and understanding how evolution worked to select and keep the most appropriate systems for cyanobacteria to develop in the quite different environments that they have successfully colonized.

Structure, function, and mechanism of the core circadian clock in cyanobacteria

“…Moreover, the relevant active domains of the components may reside within a single protein that has both kinase and substrate functions. Cross-talk between regulatory networks increases dramatically from prokaryotes to eukaryotes (60), and cyanobacteria appear to fall somewhere in the middle of this complexity. The circadian signaling network in cyanobacteria is not yet fully understood, and new components are still being identified (18,19).…”

Near-UV cyanobacteriochrome signaling system elicits negative phototaxis in the cyanobacterium Synechocystis sp. PCC 6803

“…UirS is encoded in 1 of 16 two-component signaling gene clusters in Synechocystis (19). This cluster also harbors two response regulator genes, slr1213 (hereafter designated uirR for UV intensity response Regulator) and slr1214 (hereafter designated lsiR for light and stress integrating response Regulator) (Fig.…”

The ancestral symbiont sensor kinase CSK links photosynthesis with gene expression in chloroplasts

“…Two-component signal transduction is ubiquitous in prokaryotes (5), including cyanobacteria (6). Its components are a sensor kinase, phosphorylated on histidine when a specific environmental change occurs; and a response regulator that contains an aspartate residue to which the phosphate group is transferred, activating an appropriate response (5).…”