title: Noncanonical Photocycle Initiation Dynamics of the Photoactive Yellow Protein (PYP) Domain of the PYP-Phytochrome-Related (Ppr) Photoreceptor.
abstract: The photoactive yellow protein (PYP) from Halorhodospira halophila (Hhal) is a bacterial photoreceptor and model system for exploring functional protein dynamics. We report ultrafast spectroscopy experiments that probe photocycle initiation dynamics in the PYP domain from the multidomain PYP-phytochrome-related photoreceptor from Rhodospirillum centenum (Rcen). As with Hhal PYP, Rcen PYP exhibits similar excited-state dynamics; in contrast, Rcen PYP exhibits altered photoproduct ground-state dynamics in which the primary I0intermediate as observed in Hhal PYP is absent. This property is attributed to a tighter, more sterically constrained binding pocket around the p-coumaric acid chromophore due to a change in the Rcen PYP protein structure that places Phe98 instead of Met100 in contact with the chromophore. Hence, the I0state is not a necessary step for the initiation of productive PYP photocycles and the ubiquitously studied Hhal PYP may not be representative of the broader PYP family of photodynamics.
authors.affiliation: Department of Chemistry, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
authors.forename: L Tyler
authors.initials: LT
authors.lastname: Mix
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University , Stillwater, Oklahoma 74078, United States.
authors.forename: Miwa
authors.initials: M
authors.lastname: Hara
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University , Stillwater, Oklahoma 74078, United States.
authors.forename: Rachana
authors.initials: R
authors.lastname: Rathod
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University , Stillwater, Oklahoma 74078, United States.
authors.forename: Masato
authors.initials: M
authors.lastname: Kumauchi
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University , Stillwater, Oklahoma 74078, United States.
authors.forename: Wouter D
authors.initials: WD
authors.lastname: Hoff
authors.affiliation: Department of Chemistry, University of California, Davis , One Shields Avenue, Davis, California 95616, United States.
authors.forename: Delmar S
authors.identifier: http://orcid.org/0000-0003-4522-2689
authors.initials: DS
authors.lastname: Larsen
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D003373:Coumaric Acids; D020607:Halorhodospira halophila; D020283:Photoreceptors, Microbial / Q000737:chemistry*; D010834:Phytochrome / Q000378:metabolism; D011422:Propionates; D013057:Spectrum Analysis
chemical_list: D001426:Bacterial Proteins; D003373:Coumaric Acids; D020283:Photoreceptors, Microbial; D011422:Propionates; C050162:photoactive yellow protein, Bacteria; D010834:Phytochrome; C495469:p-coumaric acid