Top Highlights

• The cikA (circadian input kinase) gene encodes a bacteriophytochrome-like histidine kinase involved in the input signaling of the clock
• he concentration and redox state of quinones in a cell is light dependent. Mutants that are cikA-deficient have a shorter circadian period of gene expression and altered phasing of rhythmicity
• he N-terminal region upstream of the GAF domain was previously shown to enhance phosphorylation of the HisKA domain (Mutsuda et al., 2003), however, no specific fragment of this region was identified as a major contributor to this function.
• Motif 1 seems to be primarily functional: most of its residues are exposed and seven of them are determined as functionally important

Domain