Resonance Raman characterization of Rhodobacter capsulatus reaction centers with lysine mutations near the accessory bacteriochlorophylls.
Lysine residues have been introduced into Rhodobacter capsulatus reaction centers at M-polypeptide position 201 and at L-polypeptide position 178. These positions are in the proximity of ring V of the accessory bacterochlorophylls BA and BB, respectively. Resonance Raman studies indicate that the introduction of a Lys residue at either position M201 or L178 results in structural perturbations to the BChl cofactors. Lys at L178 directly interacts with BB, most likely via a hydrogen bond. The hydrogen bonding interaction is consistent with enhanced B branch electron transfer that is observed in RCs from the S(L178)K/G(M201)D/L(M212)H triple mutant versus the G(M201)D/L(M212)H double mutant. In contrast, the introduction of a Lys at M201 does not result in hydrogen bonding to the BA cofactor, in contrast to the introduction of a His at M201. Accordingly, the alkyl ammonium head group of the side chain of the Lys at M201 residue appears to be distant from BA.
Chen
Lei
L
Department of Chemistry, University of California, Riverside, CA 92521-0403, USA.
Kirmaier
Christine
C
Holten
Dewey
D
Bocian
David F
DF
D001429:Bacteriochlorophylls / Q000737:chemistry / Q000378:metabolism*; D008239:Lysine / Q000235:genetics* / Q000378:metabolism; D008715:Methionine / Q000235:genetics / Q000378:metabolism; D015394:Molecular Structure; D009154:Mutation / Q000235:genetics*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016354:Rhodobacter capsulatus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013059:Spectrum Analysis, Raman
D001429:Bacteriochlorophylls; D045322:Photosynthetic Reaction Center Complex Proteins; D008715:Methionine; D008239:Lysine