Web Release Date: June 21,
The Crystal Structure of Cytochrome P460 of Nitrosomonas europaea Reveals a
Novel Cytochrome Fold and Heme-Protein Cross-link
and
Department of Biochemistry, Molecular Biology and Biophysics, The University of Minnesota, Minneapolis, Minnesota 55455, and Rigaku Americas Corporation, 9009 New Trails Drive, The Woodlands, Texas 77381
Received January 16, 2007
Revised Manuscript Received May 12, 2007
Abstract:
We have determined the 1.8 Å X-ray crystal structure of a monoheme c-type cytochrome,
cytochrome P460, from Nitrosomonas europea. The chromophore possesses unusual spectral properties
analogous to those of the catalytic heme P460 of hydroxylamine oxidoreductase (HAO), the only known
heme in biology to withdraw electrons from an iron-coordinated substrate. The analysis reveals a
homodimeric structure and elucidates a new c-type cytochrome fold that is predominantly 
-sheet. In
addition to the two cysteine thioether links to the porphyrin typical of c-type hemes, there is a third
proteinaceous link involving a conserved lysine. The covalent bond is between the lysine side-chain nitrogen
and the 13'-meso carbon of the heme, which, following cross-link formation, is sp3-hybridized,
demonstrating the loss of conjugation at this position within the porphyrin. The structure has implications
for the analogous tyrosine-heme meso carbon cross-link observed in HAO.
Download the full text: PDF | HTML
