Structural highlights
Function
BFR_ECOLI Iron-storage protein, whose ferroxidase center binds Fe(2+) ions, oxidizes them by dioxygen to Fe(3+), and participates in the subsequent Fe(3+) oxide mineral core formation within the central cavity of the protein complex. The mineralized iron core can contain as many as 2700 iron atoms/24-meric molecule.[1] [2]
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.
See Also
References
- ↑ Yang X, Le Brun NE, Thomson AJ, Moore GR, Chasteen ND. The iron oxidation and hydrolysis chemistry of Escherichia coli bacterioferritin. Biochemistry. 2000 Apr 25;39(16):4915-23. PMID:10769150
- ↑ Baaghil S, Lewin A, Moore GR, Le Brun NE. Core formation in Escherichia coli bacterioferritin requires a functional ferroxidase center. Biochemistry. 2003 Dec 2;42(47):14047-56. PMID:14636073 doi:http://dx.doi.org/10.1021/bi035253u
- ↑ Hingorani K, Pace R, Whitney S, Murray JW, Smith P, Cheah MH, Wydrzynski T, Hillier W. Photo-oxidation of tyrosine in a bio-engineered bacterioferritin 'reaction centre'-A protein model for artificial photosynthesis. Biochim Biophys Acta. 2014 Aug 5. pii: S0005-2728(14)00557-X. doi:, 10.1016/j.bbabio.2014.07.019. PMID:25107631 doi:http://dx.doi.org/10.1016/j.bbabio.2014.07.019
