title: How light-induced charge transfer accelerates the receptor-state recovery of photoactive yellow protein from its signaling state.
abstract: Stark (electroabsorption) spectra of the M100A mutant of photoactive yellow protein reveal that the neutral, cis cofactor of the pB intermediate undergoes a strikingly large change in the static dipole moment (|Deltamu| = 19 Debye) on photon absorption. The formation of this charge-separated species, in the excited state, precedes the cis --> trans isomerization of the pB cofactor and the regeneration of pG. The large |Deltamu|, reminiscent of that produced on the excitation of pG, we propose, induces twisting of the cis cofactor as a result of translocation of negative charge, from the hydroxyl oxygen, O1, toward the C7-C8 double bond. The biological significance of this photoinduced charge transfer reaction underlies the significantly faster regeneration of pG from pB in vitro, on the absorption of blue light.
authors.affiliation: Department of Biophysics and Physics of Complex Systems, Faculty of Sciences, Vrije Universiteit, Amsterdam, The Netherlands. lp2f@few.vu.nl
authors.forename: L
authors.initials: L
authors.lastname: Premvardhan
authors.forename: M A
authors.initials: MA
authors.lastname: van der Horst
authors.forename: K J
authors.initials: KJ
authors.lastname: Hellingwerf
authors.forename: R
authors.initials: R
authors.lastname: van Grondelle
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology / Q000528:radiation effects; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D008027:Light; D016297:Mutagenesis, Site-Directed; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000528:radiation effects*; D011829:Radiation Dosage
chemical_list: D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; C050162:photoactive yellow protein, Bacteria