Journal Article

Plant UVR8 Photoreceptor Senses UV-B by Tryptophan-Mediated Disruption of Cross-Dimer Salt Bridges

Getzoff, Elizabeth D., Hitomi, Kenichi, Baxter, Katherine J., Pratt, Ashley J., Christie, John M., Arvai, Andrew S., O'Hara, Andrew, Hothorn, Michael, Jenkins, Gareth I., Heilmann, Monika, Kelly, Sharon M., Smith, Brian O.

2012

Overview

The recently identified plant photoreceptor UVR8 (UV RESISTANCE LOCUS 8) triggers regulatory changes in gene expression in response to ultraviolet-B (UV-B) light through an unknown mechanism. Here, cristallographie and solution structures of the UVR8 homodimer, together with mutagenesis and far-UV circular dichroism spectroscopy, reveal its mechanisms for UV-B perception and signal transduction. ß-propeller subunits form a remarkable, tryptophan-dominated, dimer interface stitched together by a complex salt-bridge network. Salt-bridging arginines flank the excitonically coupled cross-dimer tryptophan \"pyramid\" responsible for UV-B sensing. Photoreception reversibly disrupts salt bridges, triggering dimer dissociation and signal initiation. Mutation of a single tryptophan to phenylalanine retunes the photoreceptor to detect UV-C wavelengths. Our analyses establish how UVR8 functions as a photoreceptor without a prosthetic chromophore to promote plant development and survival in sunlight.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science
• Subject: Agronomy. Soil science and plant productions / Arabidopsis - physiology / Arabidopsis Proteins - chemistry / Arabidopsis Proteins - genetics / Arabidopsis Proteins - metabolism / Arginine - chemistry / Biological and medical sciences / Biology / Chromophores / Chromosomal Proteins, Non-Histone - chemistry / Chromosomal Proteins, Non-Histone - genetics / Chromosomal Proteins, Non-Histone - metabolism / Circular Dichroism / circular dichroism spectroscopy / Crystal structure / Crystallography, X-Ray / Dimers / dissociation / Excitons / Flowers & plants / Fundamental and applied biological sciences. Psychology / Gene expression / gene expression regulation / Genetics and breeding of economic plants / Hydrogen Bonding / Hydrogen-Ion Concentration / Light / Light Signal Transduction / loci / Models, Molecular / Monomers / Mutagenesis / Networks / Perception / Phenylalanine / Photoreception / Photoreceptors / Photoreceptors, Plant - chemistry / Photoreceptors, Plant - genetics / Photoreceptors, Plant - metabolism / Plant biology / Plant breeding: fundamental aspects and methodology / plant development / prostheses / Protein Conformation / Protein Multimerization / Proteins / Recombinant Fusion Proteins - chemistry / Recombinant Fusion Proteins - metabolism / Salts / signal transduction / solar radiation / Sunlight / Tryptophan / Tryptophan - chemistry / Ultraviolet radiation / Ultraviolet Rays / Varietal selection. Specialized plant breeding, plant breeding aims / Wavelengths