Premium
The Cytochrome‐ c Binding Surface of Reaction Centers from Rhodobacter sphaeroides
Author(s) -
Tiede David M.,
Chang ChongHwan
Publication year - 1988
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198800029
Subject(s) - chemistry , rhodobacter sphaeroides , photosynthetic reaction centre , cytochrome , crystallography , periplasmic space , cytochrome c , protein subunit , stereochemistry , electron transfer , photochemistry , photosynthesis , enzyme , biochemistry , escherichia coli , mitochondrion , gene
In this paper, we describe the water‐exposed, periplasmic surface of the bacterial photosynthetic reaction center from Rhodobacter sphaeroides R‐26. This surface contains binding sites for c ‐type cytochromes. The approximate two‐fold structural symmetry is evident in the folding of the L and M subunits of the reaction center on this surface. In spite of this, the distribution of charged residues shows a marked deviation from symmetry. One group of charged residues is distributed symmetrically. For this group, equivalently charged residues are located at symmetry‐related positions on both L and M subunits. However, charged residues are also found at positions which do not follow the two‐fold symmetry. Seven charged residues appear on the L and M subunits at positions which do not have a charged residue at the corresponding position on the other subunit. These symmetry‐breaking charged residues appear in a single region, or “patch”, on the surface of the reaction center. We propose that this patch may function as a site for cytochrome c docking. A model of the Rb. sphaeroides cytochrome c 2 ‐reaction center electron transfer complex has been built. Preliminary energy calculations show that this configuration is at least a local energy minimum.