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Titel: Proton-Coupled Electron Transport in Two Distinct CYBASC Paralogs of Arabidopsis thaliana: A Comparative Characterization of Highly Conserved Tyrosine and Lysine Residues
VerfasserIn: Klein, Martin
Deniz, Erhan
Heit, Sabine
Wille, Georg
Mäntele, Werner
Lancaster, C. Roy D.
Sprache: Englisch
Titel: Biochemistry
Bandnummer: 59
Heft: 25
Seiten: 2328-2339
Verlag/Plattform: ACS
Erscheinungsjahr: 2020
Freie Schlagwörter: Bioinorganic Chemistry
Crystal Structure
Monomers
Peptides And Proteins
Redox Reactions
DDC-Sachgruppe: 610 Medizin, Gesundheit
Dokumenttyp: Journalartikel / Zeitschriftenartikel
Abstract: CYBASC proteins are ascorbate (AscH−) reducible, diheme b-containing integral membrane cytochrome b561 proteins (cytb561), which are proposed to be involved in AscH− recycling and facilitation of iron absorption. Two distinct CYBASC paralogs from the plant Arabidopsis thaliana, Atcytb561-A (A-paralog) and Atcytb561-B (B-paralog), have been found to differ in their visiblespectral characteristics and their interaction with AscH− and ferric iron chelates. A previously determined crystal structure of the Bparalog provides the first insights into the structural organization of a CYBASC member and implies hydrogen bonding between the substrate AscH− and the conserved lysine residues at positions 77 (B-K77) and 81 (B-K81). The function of the highly conserved tyrosine at position 70 (B-Y70) is not obvious in the crystal structure, but its localization indicates the possible involvement in proton-coupled electron transfer. Here we show that B-Y70 plays a major role in the modulation of the oxidation−reduction midpoint potential of the high-potential heme, EM(bH), as well as in AscH− oxidation. Our results support the involvement of the functionally conserved B-K77 in the stabilization of the dianion Asc2−. These findings are supported by the crystal structure of the Bparalog, but a comparative biochemical and biophysical characterization of the A- and B-paralogs implied distinct and more complex functions of the corresponding residues A-Y69 and A-K76 in the A-paralog. Our results emphasize the need for a high-resolution crystal structure of the A-paralog to illuminate the differences in functional organization between the two paralogs.
DOI der Erstveröffentlichung: 10.1021/acs.biochem.0c00155
URL der Erstveröffentlichung: https://pubs.acs.org/doi/10.1021/acs.biochem.0c00155
Link zu diesem Datensatz: urn:nbn:de:bsz:291--ds-434594
hdl:20.500.11880/38958
http://dx.doi.org/10.22028/D291-43459
ISSN: 1520-4995
0006-2960
Datum des Eintrags: 14-Nov-2024
Bezeichnung des in Beziehung stehenden Objekts: Supporting Information
In Beziehung stehendes Objekt: https://pubs.acs.org/doi/suppl/10.1021/acs.biochem.0c00155/suppl_file/bi0c00155_si_001.pdf
Fakultät: M - Medizinische Fakultät
Fachrichtung: M - Biophysik
Professur: M - Prof. Dr. C. Roy D. Lancaster
Sammlung:SciDok - Der Wissenschaftsserver der Universität des Saarlandes

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