Signal transduction in the photoactive yellow protein. II. Proton transfer initiates conformational changes.
Molecular dynamics simulation techniques, together with semiempirical PM3 calculations, have been used to investigate the effect of photoisomerization of the 4-hydroxy-cinnamic acid chromophore on the structural properties of the photoactive yellow protein (PYP) from Ectothiorodospira halophila. In this bacteria, exposure to blue light leads to a negative photoactic response. The calculations suggest that the isomerization does not directly destabilize the protein. However, because of the isomerization, a proton transfer from a glutamic acid residue (Glu46) to the phenolate oxygen atom of the chromophore becomes energetically favorable. The proton transfer initiates conformational changes within the protein, which are in turn believed to lead to signaling.
Groenhof
Gerrit
G
Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, Rijksuniversiteit Groningen, Groningen, The Netherlands.
Lensink
Marc F
MF
Berendsen
Herman J C
HJ
Mark
Alan E
AE
D001426:Bacterial Proteins / Q000737:chemistry*; D001692:Biological Transport; D003198:Computer Simulation; D003373:Coumaric Acids / Q000737:chemistry*; D007536:Isomerism; D007700:Kinetics; D008958:Models, Molecular; D017785:Photons; D020283:Photoreceptors, Microbial / Q000737:chemistry*; D011422:Propionates; D011487:Protein Conformation; D015398:Signal Transduction
D001426:Bacterial Proteins; D003373:Coumaric Acids; D020283:Photoreceptors, Microbial; D011422:Propionates; C050162:photoactive yellow protein, Bacteria; C495469:p-coumaric acid