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SIGNAL TRANSDUCTION BY PHYTOCHROME: PHYTOCHROMES HAVE A MODULE RELATED TO THE TRANSMITTER MODULES OF BACTERIAL SENSOR PROTEINS
Author(s) -
SchneiderPoetsch Hansjörg A. W.
Publication year - 1992
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1992.tb02241.x
Subject(s) - phytochrome , histidine kinase , histidine , response regulator , biology , phytochrome a , biochemistry , phosphorylation , two component regulatory system , conserved sequence , microbiology and biotechnology , tyrosine , signal transduction , kinase , sh2 domain , peptide sequence , receptor tyrosine kinase , amino acid , arabidopsis , gene , botany , bacterial protein , mutant , red light
— A C‐terminal section of phytochromes turned out to share sequence homologies with the full length of the transmitter modules (about 250 amino acids) of bacterial sensor proteins. Coinciding hydrophobic clusters within the homologous domains imply that the overall folding of the two different types of peptides is similar. Hence, phytochromes appear to possess the structural prerequisites to transmit signals in a way bacterial sensor proteins do. The bacterial sensor proteins are known to be environmental stimuli‐regulated kinases belonging to two‐component systems. After sensing a stimulus by the N‐terminal part of the sensor protein, conformational alterations confer the signal to its (mostly) C‐terminal transmitter module which in turn is transitionally autophosphorylated at a conserved histidine. From the histidine the phosphate is transferred to the receiver module of a system‐specific regulator protein which eventually acts on transcription or enzyme activity. The histidine is not conserved in phytochromes. Instead, a conserved tyrosine is found spatially very close to the histidine position. This tyrosine might play the role of histidine, and kinase function might be associated with this part of phytochrome. In spite of this divergence, the structural similarities point to a common evolutionary origin of the phytochrome and bacterial modules.