3g7f
Crystal structure of Blastochloris viridis heterodimer mutant reaction center
Structural highlights
FunctionRCEH_BLAVI The reaction center is a membrane-bound complex that mediates the initial photochemical event in the electron transfer process of photosynthesis. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHeterodimer mutant reaction centers (RCs) of Blastochloris viridis were crystallized using microfluidic technology. In this mutant, a leucine residue replaced the histidine residue which had acted as a fifth ligand to the bacteriochlorophyll (BChl) of the primary electron donor dimer M site (HisM200). With the loss of the histidine-coordinated Mg, one bacteriochlorophyll of the special pair was converted into a bacteriopheophytin (BPhe), and the primary donor became a heterodimer supermolecule. The crystals had dimensions 400 x 100 x 100 microm, belonged to space group P4(3)2(1)2, and were isomorphous to the ones reported earlier for the wild type (WT) strain. The structure was solved to a 2.5 A resolution limit. Electron-density maps confirmed the replacement of the histidine residue and the absence of Mg. Structural changes in the heterodimer mutant RC relative to the WT included the absence of the water molecule that is typically positioned between the M side of the primary donor and the accessory BChl, a slight shift in the position of amino acids surrounding the site of the mutation, and the rotation of the M194 phenylalanine. The cytochrome subunit was anchored similarly as in the WT and had no detectable changes in its overall position. The highly conserved tyrosine L162, located between the primary donor and the highest potential heme C(380), revealed only a minor deviation of its hydroxyl group. Concomitantly to modification of the BChl molecule, the redox potential of the heterodimer primary donor increased relative to that of the WT organism (772 mV vs. 517 mV). The availability of this heterodimer mutant and its crystal structure provides opportunities for investigating changes in light-induced electron transfer that reflect differences in redox cascades. Structural and spectropotentiometric analysis of Blastochloris viridis heterodimer mutant reaction center.,Ponomarenko NS, Li L, Marino AR, Tereshko V, Ostafin A, Popova JA, Bylina EJ, Ismagilov RF, Norris JR Jr Biochim Biophys Acta. 2009 Sep;1788(9):1822-31. Epub 2009 Jun 17. PMID:19539602[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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