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Controlling Electron Transfer between the Two Cofactor Chains of Photosystem I by the Redox State of One of Their Components

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dc.contributor.authorSantabarbara, Stefano
dc.contributor.authorBullock, Bradford
dc.contributor.authorRappaport, Fabrice
dc.contributor.authorRedding, Kevin E.
dc.contributor.otherArizona State University
dc.contributor.otherArizona State University-Tempe
dc.contributor.otherUDICE-French Research Universities
dc.contributor.otherSorbonne Universite
dc.contributor.otherCentre National de la Recherche Scientifique (CNRS)
dc.contributor.otherCNRS - National Institute for Biology (INSB)
dc.contributor.otherConsiglio Nazionale delle Ricerche (CNR)
dc.contributor.otherIstituto di Biofisica (IBF-CNR)
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.date.accessioned2023-09-28T19:11:30Z
dc.date.available2023-09-28T19:11:30Z
dc.date.issued2015
dc.description.abstractTwo functional electron transfer (ET) chains, related by a pseudo-C-2 symmetry, are present in the reaction center of photosystem I (PSI). Due to slight differences in the environment around the cofactors of the two branches, there are differences in both the kinetics of ET and the proportion of ET that occurs on the two branches. The strongest evidence that this is indeed the case relied on the observation that the oxidation rates of the reduced phylloquinone (PhQ) cofactor differ by an order of magnitude. Site-directed mutagenesis of residues involved in the respective PhQ-binding sites resulted in a specific alteration of the rates of semiquinone oxidation. Here, we show that the PsaA-F689N mutation results in an similar to 100-fold decrease in the observed rate of PhQ(A)(-) oxidation. This is the largest change of PhQ(A)(-) oxidation kinetics observed so far for a single-point mutation, resulting in a lifetime that exceeds that of the terminal electron donor, P-700(+). This situation allows a second photochemical charge separation event to be initiated before PhQ(A)(-) has decayed, thereby mimicking in PSI a situation that occurs in type II reaction centers. The results indicate that the presence of PhQ(A)(-) does not impact the overall quantum yield and leads to an almost complete redistribution of the fractional utilization of the two functional ET chains, in favor of the one that does not bear the charged species. The evolutionary implications of these results are also briefly discussed.en_US
dc.format.mediumelectronic
dc.format.mimetypeapplication/pdf
dc.identifier.citationSantabarbara, S., Bullock, B., Rappaport, F., & Redding, K. E. (2015). Controlling Electron Transfer between the Two Cofactor Chains of Photosystem I by the Redox State of One of Their Components. In Biophysical Journal (Vol. 108, Issue 6, pp. 1537–1547). Elsevier BV. https://doi.org/10.1016/j.bpj.2015.01.009
dc.identifier.doi10.1016/j.bpj.2015.01.009
dc.identifier.orcidhttps://orcid.org/0000-0003-2819-4022
dc.identifier.orcidhttps://orcid.org/0000-0002-7993-2614
dc.identifier.urihttps://ir.ua.edu/handle/123456789/10994
dc.languageEnglish
dc.language.isoen_US
dc.publisherCell Press
dc.subjectIRON-SULFUR CLUSTER
dc.subjectREACTION-CENTER SUBUNITS
dc.subjectF-X
dc.subjectCHLAMYDOMONAS-REINHARDTII
dc.subjectCRYSTAL-STRUCTURE
dc.subjectREACTION CENTERS
dc.subjectHYDROGEN-BOND
dc.subjectRADICAL PAIR
dc.subjectTEMPERATURE-DEPENDENCE
dc.subjectPHYLLOQUINONE
dc.subjectBiophysics
dc.titleControlling Electron Transfer between the Two Cofactor Chains of Photosystem I by the Redox State of One of Their Componentsen_US
dc.typeArticle
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