Eukaryotic phytochromes: light-regulated serine/threonine protein kinases with histidine kinase ancestry.
The discovery of cyanobacterial phytochrome histidine kinases, together with the evidence that phytochromes from higher plants display protein kinase activity, bind ATP analogs, and possess C-terminal domains similar to bacterial histidine kinases, has fueled the controversial hypothesis that the eukaryotic phytochrome family of photoreceptors are light-regulated enzymes. Here we demonstrate that purified recombinant phytochromes from a higher plant and a green alga exhibit serine/threonine kinase activity similar to that of phytochrome isolated from dark grown seedlings. Phosphorylation of recombinant oat phytochrome is a light- and chromophore-regulated intramolecular process. Based on comparative protein sequence alignments and biochemical cross-talk experiments with the response regulator substrate of the cyanobacterial phytochrome Cph1, we propose that eukaryotic phytochromes are histidine kinase paralogs with serine/threonine specificity whose enzymatic activity diverged from that of a prokaryotic ancestor after duplication of the transmitter module.
Yeh
K C
KC
Section of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA.
Lagarias
J C
JC
D000595:Amino Acid Sequence; D000071677:Histidine Kinase; D008027:Light; D008969:Molecular Sequence Data; D010786:Photoreceptor Cells / Q000201:enzymology*; D018521:Plant Physiological Phenomena; D011494:Protein Kinases / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
D011994:Recombinant Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D000071677:Histidine Kinase