3FSZ

Pseudomonas aeruginosa Azurin with mutated metal-binding loop sequence (CAAAAHAAAAM)

Summary for 3FSZ

• Entry DOI: 10.2210/pdb3fsz/pdb
• Related: 3FS9 3FSA 3FSV 3FSW 3FT0
• Descriptor: Azurin, COPPER (II) ION (3 entities in total)
• Functional Keywords: cupredoxin fold, metal binding, protein-protein interaction, metal binding protein
• Biological source: Pseudomonas aeruginosa
• Cellular location: Periplasm: P00282
• Total number of polymer chains: 2
• Total formula weight: 27840.42

Authors

Banfield, M.J. (deposition date: 2009-01-12, release date: 2009-03-10, Last modification date: 2024-10-30)

Primary citation

Sato, K.,Li, C.,Salard, I.,Thompson, A.J.,Banfield, M.J.,Dennison, C.
Metal-binding loop length and not sequence dictates structure.
Proc.Natl.Acad.Sci.USA, 106:5616-5621, 2009

PubMed Abstract: The C-terminal copper-binding loop in the beta-barrel fold of the cupredoxin azurin has been replaced with a range of sequences containing alanine, glycine, and valine residues to assess the importance of amino acid composition and the length of this region. The introduction of 2 and 4 alanines between the coordinating Cys, His, and Met results in loop structures matching those in naturally occurring proteins with the same loop lengths. A loop with 4 alanines between the Cys and His and 3 between the His and Met ligands has a structure identical to that of the WT protein, whose loop is the same length. Loop structure is dictated by length and not sequence allowing the properties of the main surface patch for interactions with partners, to which the loop is a major contributor, to be optimized. Loops with 2 amino acids between the ligands using glycine, alanine, and valine residues have been compared. An empirical relationship is found between copper site protection by the loop and reduction potential. A loop adorned with 4 methyl groups is sufficient to protect the copper ion, enabling most sequences to adequately perform this task. The mutant with 3 alanine residues between the ligands forms a strand-swapped dimer in the crystal structure, an arrangement that has not, to our knowledge, been seen previously for this family of proteins. Cupredoxins function as redox shuttles and are required to be monomeric; therefore, none have evolved with a metal-binding loop of this length.

PubMed: 19299503
DOI: 10.1073/pnas.0811324106

Experimental method

X-RAY DIFFRACTION (2 Å)