The thylakoid compartments of plant chloroplasts are a vital destination for copper. Copper is needed to form holo-plastocyanin, which must shuttle electrons between photosystems to convert light into biologically useful chemical energy. Copper can bind tightly to proteins, so it has been hypothesized that copper partitions onto ligand-exchange pathways to reach intracellular locations without inflicting damage en route. The copper metallochaperone Atx1 of chloroplast-related cyanobacteria (ScAtx1) engages in bacterial two-hybrid interactions with N-terminal domains of copper-transporting ATPases CtaA (cell import) and PacS (thylakoid import). Here we visualize copper delivery. The N-terminal domain PacSN has a ferredoxin-like fold that forms copper-dependent heterodimers with ScAtx1. Removal of copper, by the addition of the cuprous-ion chelator bathocuproine disulfonate, disrupts this heterodimer, as shown from a reduction of the overall tumbling rate of the protein mixture. The NMR spectral changes of the heterodimer versus the separate proteins reveal that loops 1, 3, and 5 (the carboxyl tail) of the ScAtx1 Cu(I) site switch to an apo-like configuration in the heterodimer. NMR data ( 2JNH couplings in the imidazole ring of 15N ScAtx1 His-61) also show that His-61, bound to copper(I) in [Cu(I)ScAtX1] 2, is not coordinated to copper in the heterodimer. A model for the PacSN/Cu(I)/ScAtx1 complex is presented. Contact with PacS N induces change to the ScAtx1 copper-coordination sphere that drives copper release for thylakoid import. These data also elaborate on the mechanism to keep copper(I) out of the ZiaAN ATPase zinc sites. © 2006 by The National Academy of Sciences of the USA.

The delivery of copper for thylakoid import observed by NMR / L.Banci; I.Bertini; S.Ciofi-Baffoni; N.G.Kandias; N.J.Robinson; G.A.Spyroulias; X.C.Su; S.Tottey; M.Vanarotti. - In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA. - ISSN 0027-8424. - STAMPA. - 103:(2006), pp. 8320-8325. [10.1073/pnas.0600142103]

The delivery of copper for thylakoid import observed by NMR

BANCI, LUCIA;BERTINI, IVANO;CIOFI BAFFONI, SIMONE;
2006

Abstract

The thylakoid compartments of plant chloroplasts are a vital destination for copper. Copper is needed to form holo-plastocyanin, which must shuttle electrons between photosystems to convert light into biologically useful chemical energy. Copper can bind tightly to proteins, so it has been hypothesized that copper partitions onto ligand-exchange pathways to reach intracellular locations without inflicting damage en route. The copper metallochaperone Atx1 of chloroplast-related cyanobacteria (ScAtx1) engages in bacterial two-hybrid interactions with N-terminal domains of copper-transporting ATPases CtaA (cell import) and PacS (thylakoid import). Here we visualize copper delivery. The N-terminal domain PacSN has a ferredoxin-like fold that forms copper-dependent heterodimers with ScAtx1. Removal of copper, by the addition of the cuprous-ion chelator bathocuproine disulfonate, disrupts this heterodimer, as shown from a reduction of the overall tumbling rate of the protein mixture. The NMR spectral changes of the heterodimer versus the separate proteins reveal that loops 1, 3, and 5 (the carboxyl tail) of the ScAtx1 Cu(I) site switch to an apo-like configuration in the heterodimer. NMR data ( 2JNH couplings in the imidazole ring of 15N ScAtx1 His-61) also show that His-61, bound to copper(I) in [Cu(I)ScAtX1] 2, is not coordinated to copper in the heterodimer. A model for the PacSN/Cu(I)/ScAtx1 complex is presented. Contact with PacS N induces change to the ScAtx1 copper-coordination sphere that drives copper release for thylakoid import. These data also elaborate on the mechanism to keep copper(I) out of the ZiaAN ATPase zinc sites. © 2006 by The National Academy of Sciences of the USA.
2006
103
8320
8325
L.Banci; I.Bertini; S.Ciofi-Baffoni; N.G.Kandias; N.J.Robinson; G.A.Spyroulias; X.C.Su; S.Tottey; M.Vanarotti
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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/310589
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