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Fortino M, Schifino G, Vitone D, Arnesano F, Pietropaolo A. The stepwise dissociation of the Zn(II)-bound Atox1 homodimer and its energetic asymmetry. Inorganica Chim Acta 2023. [DOI: 10.1016/j.ica.2023.121452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
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Crystal Structure of the Human Copper Chaperone ATOX1 Bound to Zinc Ion. Biomolecules 2022; 12:biom12101494. [PMID: 36291703 PMCID: PMC9599288 DOI: 10.3390/biom12101494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/09/2022] [Accepted: 10/10/2022] [Indexed: 11/17/2022] Open
Abstract
The bioavailability of copper (Cu) in human cells may depend on a complex interplay with zinc (Zn) ions. We investigated the ability of the Zn ion to target the human Cu-chaperone Atox1, a small cytosolic protein capable of anchoring Cu(I), by a conserved surface-exposed Cys-X-X-Cys (CXXC) motif, and deliver it to Cu-transporting ATPases in the trans-Golgi network. The crystal structure of Atox1 loaded with Zn displays the metal ion bridging the CXXC motifs of two Atox1 molecules in a homodimer. The identity and location of the Zn ion were confirmed through the anomalous scattering of the metal by collecting X-ray diffraction data near the Zn K-edge. Furthermore, soaking experiments of the Zn-loaded Atox1 crystals with a strong chelating agent, such as EDTA, caused only limited removal of the metal ion from the tetrahedral coordination cage, suggesting a potential role of Atox1 in Zn metabolism and, more generally, that Cu and Zn transport mechanisms could be interlocked in human cells.
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Liu H, Lu Y, Wolf B, Saer R, King JD, Blankenship RE. Photoactivation and relaxation studies on the cyanobacterial orange carotenoid protein in the presence of copper ion. PHOTOSYNTHESIS RESEARCH 2018; 135:143-147. [PMID: 28271249 DOI: 10.1007/s11120-017-0363-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 02/24/2017] [Indexed: 06/06/2023]
Abstract
Photosynthesis starts with absorption of light energy by light-harvesting antenna complexes with subsequent production of energy-rich organic compounds. However, all photosynthetic organisms face the challenge of excess photochemical conversion capacity. In cyanobacteria, non-photochemical quenching (NPQ) performed by the orange carotenoid protein (OCP) is one of the most important mechanisms to regulate the light energy captured by light-harvesting antennas. This regulation permits the cell to meet its cellular energy requirements and at the same time protects the photosynthetic apparatus under fluctuating light conditions. Several reports have revealed that thermal dissipation increases under excess copper in plants. To explore the effects and mechanisms of copper on cyanobacteria NPQ, photoactivation and relaxation of OCP in the presence of copper were examined in this communication. When OCPo (OCP at orange state) is converted into OCPr(OCP at red state), copper ion has no effect on the photoactivation kinetics. Relaxation of OCPr to OCPo, however, is largely delayed-almost completely blocked, in the presence of copper. Even the addition of the fluorescence recovery protein (FRP) cannot activate the relaxation process. Native polyacrylamide gel electrophoresis (PAGE) analysis result indicates the heterogeneous population of Cu2+-locked OCPr. The Cu2+-OCP binding constant was estimated using a hyperbolic binding curve. Functional roles of copper-binding OCP in vivo are discussed.
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Affiliation(s)
- Haijun Liu
- Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO, 63130, USA
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Yue Lu
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA
- Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Benjamin Wolf
- Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO, 63130, USA
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Rafael Saer
- Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO, 63130, USA
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Jeremy D King
- Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO, 63130, USA
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Robert E Blankenship
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA.
- Photosynthetic Antenna Research Center, Washington University in St. Louis, St. Louis, MO, 63130, USA.
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA.
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