4A4J

Crosstalk between Cu(I) and Zn(II) homeostasis

Summary for 4A4J

• Entry DOI: 10.2210/pdb4a4j/pdb
• Related: 2GCF 2XMW 4A47 4A48
• Descriptor: COPPER-TRANSPORTING ATPASE PACS, ZINC ION (3 entities in total)
• Functional Keywords: hydrolase, copper homeostasis, zinc homeostasis, atx1, metal-transporting atpases
• Biological source: SYNECHOCYSTIS
• Cellular location: Cell membrane; Multi-pass membrane protein: P73241
• Total number of polymer chains: 1
• Total formula weight: 7462.73

Authors

Badarau, A.,Basle, A.,Firbank, S.J.,Denninson, C. (deposition date: 2011-10-14, release date: 2012-12-12, Last modification date: 2023-12-20)

Primary citation

Badarau, A.,Basle, A.,Firbank, S.J.,Dennison, C.
Investigating the Role of Zinc and Copper Binding Motifs of Trafficking Sites in the Cyanobacterium Synechocystis Pcc 6803.
Biochemistry, 52:6816-, 2013

PubMed Abstract: Although zinc and copper are required by proteins with very different functions, these metals can be delivered to cellular locations by homologous metal transporters within the same organism, as demonstrated by the cyanobacterial ( Synechocystis PCC 6803) zinc exporter ZiaA and thylakoidal copper importer PacS. The N-terminal metal-binding domains of these transporters (ZiaAN and PacSN, respectively) have related ferredoxin folds also found in the metallochaperone Atx1, which delivers copper to PacS, but differ in the residues found in their M/IXCXXC metal-binding motifs. To investigate the role of the nonconserved residues in this region on metal binding, the sequence from ZiaAN has been introduced into Atx1 and PacSN, and the motifs of Atx1 and PacSN swapped. The motif sequence can tune Cu(I) affinity only approximately 3-fold. However, the introduction of the ZiaAN motif (MDCTSC) dramatically increases the Zn(II) affinity of both Atx1 and PacSN by up to 2 orders of magnitude. The Atx1 mutant with the ZiaAN motif crystallizes as a side-to-side homodimer very similar to that found for [Cu(I)2-Atx1]2 ( Badarau et al. Biochemistry 2010 , 49 , 7798 ). In a crystal structure of the PacSN mutant possessing the ZiaAN motif (PacSN(ZiaAN)), the Asp residue from the metal-binding motif coordinates Zn(II). This demonstrates that the increased Zn(II) affinity of this variant and the high Zn(II) affinity of ZiaAN are due to the ability of the carboxylate to ligate this metal ion. Comparison of the Zn(II) sites in PacSN(ZiaAN) structures provides additional insight into Zn(II) trafficking in cyanobacteria.

PubMed: 24050657
DOI: 10.1021/BI400492T

Experimental method

X-RAY DIFFRACTION (1.25 Å)