X-ray crystal structure of the YM210W mutant reaction centre from Rhodobacter sphaeroides

The X-ray crystal structure of a reaction centre from Rhodobacter sphaeroid es with a mutation of tyrosine M210 to tryptophan (YM210W) has been determi ned to a resolution of 2.5 Angstrom. Structural conservation is very good t hroughout the body of the protein, with the tryptophan side chain adopting a position in the mutant complex closely resembling that of the tyrosine in the wild-type complex, The spectroscopic properties of the YM210W reaction centre are discussed with reference to the structural data, with particula r focus on evidence that the introduction of the bulkier tryptophan in plac e of the native tyrosine may cause a small tilt of the macrocycle of the B- L monomeric bacteriochlorophyll. (C) 2000 Federation of European Biochemica l Societies.