Signal transduction in the photoactive yellow protein. II. Proton transfer initiates conformational changes

• Published in: Proteins, structure, function, and bioinformatics Vol. 48; no. 2; pp. 212 - 219
• Main Authors: Groenhof, Gerrit, Lensink, Marc F., Berendsen, Herman J. C., Mark, Alan E.
• Format: Journal Article
• Language: English
• Published: New York Wiley Subscription Services, Inc., A Wiley Company 01-08-2002
• Subjects: Bacterial Proteins - chemistry; Biological Transport; Computer Simulation; Coumaric Acids - chemistry; Isomerism; Kinetics; Models, Molecular; molecular dynamics; photoactive yellow protein; Photons; Photoreceptors, Microbial - chemistry; Propionates; Protein Conformation; proton transfer; semiempirical PM3 calculations; Signal Transduction
• ISSN: 0887-3585; 1097-0134
• DOI: 10.1002/prot.10135

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. Proteins 2002;48:212–219. © 2002 Wiley‐Liss, Inc.