Crystal structure of a novel red copper protein from Nitrosomonas europaea

Raquel L. Lieberman, David M. Arciero, Alan B. Hooper, Amy C. Rosenzweig*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


Nitrosocyanin (NC) is a mononuclear red copper protein isolated from the ammonia oxidizing bacterium Nitrosomonas europaea. Although NC exhibits some sequence homology to classic blue copper proteins, its spectroscopic and electrochemical properties are drastically different. The 1.65 Å resolution crystal structure of oxidized NC reveals an unprecedented trimer of single domain cupredoxins. Each copper center is partially covered by an unusual extended β-hairpin structure from an adjacent monomer. The copper ion is coordinated by His 98, His 103, Cys 95, a single side chain oxygen of Glu 60, and a solvent molecule. In the 2.3 Å resolution structure of reduced NC, His 98 shifts away from the copper ion, and the solvent molecule is not observed. The arrangement of these ligands renders the coordination geometry of the NC red copper center distinct from that of blue copper centers. In particular, the red copper center has a higher coordination number and lacks the long Cu-S(Met) and short Cu-S(Cys) bond distances characteristic of blue copper. Moreover, the red copper center is square pyramidal whereas blue copper is typically distorted tetrahedral. Analysis of the NC structure provides insight into possible functions of this new type of biological copper center.

Original languageEnglish (US)
Pages (from-to)5674-5681
Number of pages8
Issue number19
StatePublished - May 15 2001

ASJC Scopus subject areas

  • Biochemistry

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