3IQ5

Crystal structure of an engineered metal-free tetrameric cytochrome cb562 complex templated by Zn-coordination

Summary for 3IQ5

• Entry DOI: 10.2210/pdb3iq5/pdb
• Related: 2BC5 2QLA 3IQ6
• Descriptor: Soluble cytochrome b562, PROTOPORPHYRIN IX CONTAINING FE (3 entities in total)
• Functional Keywords: tetramer of four-helix bundles with interfacial disulfide bonds, electron transport, heme, iron, metal-binding, transport
• Biological source: Escherichia coli
• Cellular location: Periplasm: P0ABE7
• Total number of polymer chains: 4
• Total formula weight: 49270.44

Authors

Brodin, J.N.,Tezcan, F.A. (deposition date: 2009-08-19, release date: 2010-06-16, Last modification date: 2023-09-06)

Primary citation

Brodin, J.D.,Medina-Morales, A.,Ni, T.,Salgado, E.N.,Ambroggio, X.I.,Tezcan, F.A.
Evolution of metal selectivity in templated protein interfaces.
J.Am.Chem.Soc., 132:8610-8617, 2010

PubMed Abstract: Selective binding by metalloproteins to their cognate metal ions is essential to cellular survival. How proteins originally acquired the ability to selectively bind metals and evolved a diverse array of metal-centered functions despite the availability of only a few metal-coordinating functionalities remains an open question. Using a rational design approach (Metal-Templated Interface Redesign), we describe the transformation of a monomeric electron transfer protein, cytochrome cb(562), into a tetrameric assembly ((C96)RIDC-1(4)) that stably and selectively binds Zn(2+) and displays a metal-dependent conformational change reminiscent of a signaling protein. A thorough analysis of the metal binding properties of (C96)RIDC-1(4) reveals that it can also stably harbor other divalent metals with affinities that rival (Ni(2+)) or even exceed (Cu(2+)) those of Zn(2+) on a per site basis. Nevertheless, this analysis suggests that our templating strategy simultaneously introduces an increased bias toward binding a higher number of Zn(2+) ions (four high affinity sites) versus Cu(2+) or Ni(2+) (two high affinity sites), ultimately leading to the exclusive selectivity of (C96)RIDC-1(4) for Zn(2+) over those ions. More generally, our results indicate that an initial metal-driven nucleation event followed by the formation of a stable protein architecture around the metal provides a straightforward path for generating structural and functional diversity.

PubMed: 20515031
DOI: 10.1021/ja910844n

Experimental method

X-RAY DIFFRACTION (2.05 Å)