Structural basis for light control of cell development revealed by crystal structures of a myxobacterial phytochrome

IUCrJ

Tracy, G.¹  Nakane, T.²  Halavaty, A.S.³  Valera, J.⁴  Woitowich, N.C.⁵  Claesson, E.⁶  Kupitz, C.⁷  Waltz, P.⁸  Nelson, G.⁹  Pandey, S.^1,10  Tanaka, R.^1,11  Gallagher, K.D.^1,12 

[1] Center for Applied Structural Discovery, Arizona State University, 85287 Tempe, AZ, USA;Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan;Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA;Department of Biological Sciences, Graduate School of Science, University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan;Department of Biology, Northeastern Illinois University, Chicago, IL, USA;Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan;Department of Chemistry and Molecular Biology, University of Gothenburg, 40530 Gothenburg, Sweden;Department of Physics, University of Wisconsin, Milwaukee, WI, USA;Faculty of Medicine, Anatomy, University of Helsinki, 00014 Helsinki, Finland;Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan;Nanoscience Center, Department of Biological and Environmental Sciences, University of Jyvaskyla, 40014 Jyvaskyla, Finland;RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, 679-5148 Hyogo, Japan

关键词: PHYTOCHROMES;    PHOTORECEPTORS;    PHOTOSYNTHETIC BACTERIA;    MYXOBACTERIA;    ABSORPTION SPECTRA;   

DOI  :  10.1107/S2052252518010631

学科分类：数学（综合）

来源: International Union of Crystallography

【 摘 要 】

Phytochromes are red-light photoreceptors that were first characterized in plants, with homologs in photosynthetic and non-photosynthetic bacteria known as bacteriophytochromes (BphPs). Upon absorption of light, BphPs interconvert between two states denoted Pr and Pfr with distinct absorption spectra in the red and far-red. They have recently been engineered as enzymatic photoswitches for fluorescent-marker applications in non-invasive tissue imaging of mammals. This article presents cryo- and room-temperature crystal structures of the unusual phytochrome from the non-photosynthetic myxo­bacterium Stigmatella aurantiaca (SaBphP1) and reveals its role in the fruiting-body formation of this photomorphogenic bacterium. SaBphP1 lacks a conserved histidine (His) in the chromophore-binding domain that stabilizes the Pr state in the classical BphPs. Instead it contains a threonine (Thr), a feature that is restricted to several myxobacterial phytochromes and is not evolutionarily understood. SaBphP1 structures of the chromophore binding domain (CBD) and the complete photosensory core module (PCM) in wild-type and Thr-to-His mutant forms reveal details of the molecular mechanism of the Pr/Pfr transition associated with the physiological response of this myxobacterium to red light. Specifically, key structural differences in the CBD and PCM between the wild-type and the Thr-to-His mutant involve essential chromophore contacts with proximal amino acids, and point to how the photosignal is transduced through the rest of the protein, impacting the essential enzymatic activity in the photomorphogenic response of this myxobacterium.

【 授权许可】

CC BY