Title: Protein Conformational Gate Controlling Binding Site Preference and Migration for Ubiquinone-B in the Photosynthetic Reaction Center of <i>Rhodobacter </i><i>s</i><i>phaeroides</i>
Abstract:An abundance of X-ray-derived structural data exists for the photosynthetic reaction center of the purple bacteria Rhodobacter sphaeroides; yet, the preferred binding site of the secondary electron ac...An abundance of X-ray-derived structural data exists for the photosynthetic reaction center of the purple bacteria Rhodobacter sphaeroides; yet, the preferred binding site of the secondary electron acceptor ubiquinone (QB) and how its binding influences the rate of electron transfer in the system are still uncertain. Current hypotheses propose a gated electron transfer; but the identification of a gate has eluded discovery [Stowell, M. H. B.; McPhillips, T. M.; Rees, D. C.; Soltis, S. M.; Abresch, E.; Feher, G. Science 1997, 276, 812−816. Graige, M. S.; Feher, G.; Okamura, M. Y. Proc. Natl. Acad. Sci. U.S.A. 1998, 95, 11679−11684]. Suggested possibilities for the gate include the migration of QB from an inactive binding site to an electron-transfer active site, a change in orientation for QB to allow that migration, or a conformational change in the surrounding protein that either allows QB to migrate or otherwise allows electron-transfer to occur. In molecular dynamics simulations, we find that the His L190-neighboring residue Glh (Glu) L212 can compete with QB for the hydrogen bond with Nδ of His L190. In fact, this glutamic acid residue's role could be described as the conformational gate for ubiquinone binding/migration and possibly even for electron transfer.Read More
Publication Year: 2002
Publication Date: 2002-02-16
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 30
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