Chromophore conformation and the evolution of tertiary structural changes in photoactive yellow protein.
We use time-resolved crystallography to observe the structural progression of a bacterial blue light photoreceptor throughout its photocycle. Data were collected from 10 ns to 100 ms after photoactivation of the E46Q mutant of photoactive yellow protein. Refinement of transient chromophore conformations shows that the spectroscopically distinct intermediates are formed via progressive disruption of the hydrogen bond network to the chromophore. Although structural change occurs within a few nanoseconds on and around the chromophore, it takes milliseconds for a distinct pattern of tertiary structural change to fully progress through the entire molecule, thus generating the putative signaling state. Remarkably, the coupling between the chromophore conformation and the tertiary structure of this small protein is not tight: there are leads and lags between changes in the conformation of the chromophore and the protein tertiary structure.
Anderson
Spencer
S
Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA. smander@midway.uchicago.edu
Srajer
Vukica
V
Pahl
Reinhard
R
Rajagopal
Sudarshan
S
Schotte
Friedrich
F
Anfinrud
Philip
P
Wulff
Michael
M
Moffat
Keith
K
D001426:Bacterial Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray / Q000379:methods; D019992:Databases as Topic; D004583:Electrons; D008027:Light; D008958:Models, Molecular; D009154:Mutation; D020283:Photoreceptors, Microbial / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry*; D013053:Spectrophotometry; D013696:Temperature; D013997:Time Factors
D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; D011506:Proteins; C050162:photoactive yellow protein, Bacteria