4cvr

Publication Abstract from PubMed

The photosynthetic reaction centre (RC) is central to the conversion of solar energy into chemical energy and is a model for bio-mimetic engineering approaches to this end. We describe bio-engineering of a Photosystem II (PSII) RC inspired peptide model, building on our earlier studies. A non-photosynthetic haem containing bacterioferritin (BFR) from Escherichia coli that expresses as a homodimer was used as a protein scaffold, incorporating redox-active cofactors mimicking those of PSII. Desirable properties include: a di-nuclear metal binding site which provides ligands for class II metals, a hydrophobic pocket at the dimer interface which can bind a photosensitive porphyrin and presence of tyrosine residues proximal to the bound cofactors, which can be utilised as efficient electron-tunnelling intermediates. Light-induced electron transfer from proximal tyrosine residues to the photo-oxidised ZnCe6*+, in the modified BFR reconstituted with both ZnCe6 and MnII, is presented. Three site-specific tyrosine variants (Y25F, Y58F and Y45F) were made to localise the redox-active tyrosine in the engineered system. The results indicate that: presence of bound MnII is necessary to observe tyrosine oxidation in all BFR variants; Y45 the most important tyrosine as an immediate electron donor to the oxidised ZnCe6*+; and that Y25 and Y58 are both redox-active in this system, but appear to function interchangebaly. High-resolution (2.1A) crystal structures of the tyrosine variants show that there are no mutation-induced effects on the overall 3-D structure of the protein. Small effects are observed in the Y45F variant. Here, the BFR-RC represents a protein model for artificial photosynthesis.

Photo-oxidation of tyrosine in a bio-engineered bacterioferritin 'reaction centre'-A protein model for artificial photosynthesis.,Hingorani K, Pace R, Whitney S, Murray JW, Smith P, Cheah MH, Wydrzynski T, Hillier W Biochim Biophys Acta. 2014 Aug 5. pii: S0005-2728(14)00557-X. doi:, 10.1016/j.bbabio.2014.07.019. PMID:25107631^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.