A structural pathway for signaling in the E46Q mutant of photoactive yellow protein.
In the bacterial photoreceptor photoactive yellow protein (PYP), absorption of blue light by its chromophore leads to a conformational change in the protein associated with differential signaling activity, as it executes a reversible photocycle. Time-resolved Laue crystallography allows structural snapshots (as short as 150 ps) of high crystallographic resolution (approximately 1.6 A) to be taken of a protein as it functions. Here, we analyze by singular value decomposition a comprehensive time-resolved crystallographic data set of the E46Q mutant of PYP throughout the photocycle spanning 10 ns-100 ms. We identify and refine the structures of five distinct intermediates and provide a plausible chemical kinetic mechanism for their inter conversion. A clear structural progression is visible in these intermediates, in which a signal generated at the chromophore propagates through a distinct structural pathway of conserved residues and results in structural changes near the N terminus, over 20 A distant from the chromophore.
Rajagopal
Sudarshan
S
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637, USA.
Anderson
Spencer
S
Srajer
Vukica
V
Schmidt
Marius
M
Pahl
Reinhard
R
Moffat
Keith
K
D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D019992:Databases as Topic; D006860:Hydrogen Bonding; D007700:Kinetics; D015591:Microspectrophotometry; D009154:Mutation; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D015398:Signal Transduction
D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial