title: Dynamic Crystallography Reveals Early Signalling Events in Ultraviolet Photoreceptor UVR8.
abstract: Arabidopsis thalianaUVR8 (AtUVR8) is a long-sought-after photoreceptor that undergoes dimer dissociation in response to UV-B light. Crystallographic and mutational studies have identified two crucial tryptophan residues for UV-B responses inAtUVR8. However, the mechanism of UV-B perception and structural events leading up to dimer dissociation remain elusive at the molecular level. We applied dynamic crystallography to capture light-induced structural events in photoactiveAtUVR8 crystals. Here we report two intermediate structures at 1.67Å resolution. At the epicenter of UV-B signaling, concerted motions associated with Trp285/Trp233 lead to ejection of a water molecule, which weakens an intricate network of hydrogen bonds and salt bridges at the dimer interface. Partial opening of the β-propeller structure due to thermal relaxation of conformational strains originating in the epicenter further disrupts the dimer interface and leads to dimer dissociation. These dynamic crystallographic observations provide structural insights into the photo-perception and signaling mechanism of UVR8.
authors.affiliation: Key State Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei 430070, P.R. China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zeng
authors.affiliation: Renz Research Inc., Westmont, IL 60559, USA.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Ren
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong.
authors.forename: Jun
authors.initials: J
authors.lastname: Fan
authors.affiliation: Key State Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei 430070, P.R. China.
authors.forename: Pan-Pan
authors.initials: PP
authors.lastname: Peng
authors.affiliation: Key State Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei 430070, P.R. China.
authors.forename: Kun
authors.initials: K
authors.lastname: Tang
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Kowloon, Hong Kong.
authors.forename: Ruiqin
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Key State Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei 430070, P.R. China.
authors.forename: Kai-Hong
authors.initials: KH
authors.lastname: Zhao
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA ; Department of Chemistry, The University of Illinois at Chicago, Chicago, IL 60607, USA.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Yang
keywords: UVR8; dynamic crystallography; light signaling; photo-perception mechanism; photoreceptor