title: Light-induced global conformational change of photoactive yellow protein in solution.
abstract: The light-induced global conformational change of photoactive yellow protein was directly observed by small-angle X-ray scattering (SAXS). The N-terminal 6, 15, or 23 amino acid residues were enzymatically truncated (T6, T15, or T23, respectively), and their near-UV intermediates were accumulated under continuous illumination for SAXS measurements. The Kratky plot demonstrated that illumination induced partial loss of globularity. The change in globularity was marked in T6 but very small in T15 and T23, suggesting that structural change in positions 7-15 mainly reduces the globularity. The radius of gyration (R(g)) estimated by Guinier plot was increased by 1.1 A for T6 and 0.7 A for T15 and T23 upon illumination. As T23 lacks most of the N-terminal loop, structural change in the main part composed of the PAS core, helical connector, and beta-scaffold caused an increase of R(g) by 0.7 A. The structural change of positions 7-15 caused an additional increase by 0.4 A. The decrease of R(g) upon truncation of positions 7-15 for dark state was 0.3 A, while that for the intermediate was 0.7 A, suggesting that this region moves outward on formation of the intermediate. These results indicate that a light-induced structural change of PYP takes place in the main part and N-terminal 15 amino acid residues. The former induces only dimensional increase, but the latter results in additional change in shape.
authors.affiliation: Graduate School of Materials Science, Nara Institute of Science and Technology, Ikoma, Nara 630-0101, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Imamoto
authors.forename: Hironari
authors.initials: H
authors.lastname: Kamikubo
authors.forename: Miki
authors.initials: M
authors.lastname: Harigai
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Shimizu
authors.forename: Mikio
authors.initials: M
authors.lastname: Kataoka
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects; D002942:Circular Dichroism; D020607:Halorhodospira halophila / Q000737:chemistry* / Q000235:genetics; D008027:Light / Q000009:adverse effects; D008968:Molecular Conformation; D010777:Photochemistry; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects; D011487:Protein Conformation; D017510:Protein Folding; D012542:Scattering, Radiation; D012996:Solutions; D013053:Spectrophotometry; D014965:X-Rays
chemical_list: D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; D012996:Solutions; C050162:photoactive yellow protein, Bacteria