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doi:10.22028/D291-43459
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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