Identification of a hydrogen bond in the phe M197-->Tyr mutant reaction center of the photosynthetic purple bacterium Rhodobacter sphaeroides by X-ray crystallography and FTIR spectroscopy.
In bacterial reaction centers the charge separation process across the photosynthetic membrane is predominantly driven by the excited state of the bacteriochlorophyll dimer (D). An X-ray structure analysis of the Phe M197-->Tyr mutant reaction center from Rhodobacter sphaeroides at 2.7 A resolution suggests the formation of a hydrogen bond as postulated by Wachtveitl et al. [Biochemistry 32, 12875-12886, 1993] between the Tyr M197 hydroxy group and one of the 2a-acetyl carbonyls of D. In combination with electrochemically induced FTIR difference spectra showing a split band of the pi-conjugated 9-keto carbonyl of D, there is clear evidence for the existence of such a hydrogen bond.
Kuglstatter
A
A
Max-Planck-Institut für Biophysik, Heinrich-Hoffmann-Str. 7, D-60528, Frankfurt/M., Germany.
Hellwig
P
P
Fritzsch
G
G
Wachtveitl
J
J
Oesterhelt
D
D
Mäntele
W
W
Michel
H
H
D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D045342:Light-Harvesting Protein Complexes; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010084:Oxidation-Reduction; D010649:Phenylalanine / Q000737:chemistry*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000235:genetics; D012242:Rhodobacter sphaeroides / Q000737:chemistry* / Q000235:genetics; D017550:Spectroscopy, Fourier Transform Infrared; D014443:Tyrosine / Q000737:chemistry*
D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D014443:Tyrosine; D010649:Phenylalanine