title: The photoreaction of the photoactive yellow protein domain in the light sensor histidine kinase Ppr is influenced by the C-terminal domains.
abstract: To study the role of the C-terminal domains in the photocycle of a light sensor histidine kinase (Ppr) having a photoactive yellow protein (PYP) domain as the photosensor domain, we analyzed the photocycles of the PYP domain of Ppr (Ppr-PYP) and full-length Ppr. The gene fragment for Ppr-PYP was expressed in Escherichia coli, and it was chemically reconstituted with p-coumaric acid; the full-length gene of Ppr was coexpressed with tyrosine ammonia-lyase and p-coumaric acid ligase for biosynthesis in cells. The light/dark difference spectra of Ppr-PYP were pH sensitive. They were represented as a linear combination of two independent difference spectra analogous to the PYP(L)/dark and PYP(M)/dark difference spectra of PYP from Halorhodospira halophila, suggesting that the pH dependence of the difference spectra is explained by the equilibrium shift between the PYP(L)- and PYP(M)-like intermediates. The light/dark difference spectrum of Ppr showed the equilibrium shift toward PYP(L) compared with that of Ppr-PYP. Kinetic measurements of the photocycles of Ppr and Ppr-PYP revealed that the C-terminal domains accelerate the recovery of the dark state. These observations suggest an interaction between the C-terminal domains and the PYP domain during the photocycle, by which light signals captured by the PYP domain are transferred to the C-terminal domains.
authors.affiliation: Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan.
authors.forename: Hironari
authors.initials: H
authors.lastname: Kamikubo
authors.forename: Tomonori
authors.initials: T
authors.lastname: Koyama
authors.forename: Michihiro
authors.initials: M
authors.lastname: Hayashi
authors.forename: Kumiko
authors.initials: K
authors.lastname: Shirai
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Imamoto
authors.forename: Mikio
authors.initials: M
authors.lastname: Kataoka
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000528:radiation effects; D020607:Halorhodospira halophila / Q000737:chemistry / Q000378:metabolism; D000071677:Histidine Kinase; D006863:Hydrogen-Ion Concentration; D008027:Light; D010446:Peptide Fragments / Q000737:chemistry; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000378:metabolism* / Q000528:radiation effects; D011494:Protein Kinases / Q000378:metabolism*; D013053:Spectrophotometry; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D010446:Peptide Fragments; D020283:Photoreceptors, Microbial; C050162:photoactive yellow protein, Bacteria; D011494:Protein Kinases; D000071677:Histidine Kinase