Download MendeleyHigh-resolution structures of the oxidized and reduced states of cytochrome c554 from Nitrosomonas europaea.
Iverson, T.M., Arciero, D.M., Hooper, A.B., Rees, D.C.(2001) J Biol Inorg Chem 6: 390-397
- PubMed: 11372197
- DOI: https://doi.org/10.1007/s007750100213
- Primary Citation of Related Structures:
1FT5, 1FT6 - PubMed Abstract:
Cytochrome c554 (cyt c554) is a tetra-heme cytochrome involved in the oxidation of NH3 by Nitrosomonas europaea. The X-ray crystal structures of both the oxidized and dithionite-reduced states of cyt c554 in a new, rhombohedral crystal form have been solved by molecular replacement, at 1.6 A and 1.8 A resolution, respectively. Upon reduction, the conformation of the polypeptide chain changes between residues 175 and 179, which are adjacent to hemes III and IV. Cyt c554 displays conserved heme-packing motifs that are present in other heme-containing proteins. Comparisons to hydroxylamine oxidoreductase, the electron donor to cyt c554, and cytochrome c nitrite reductase, an enzyme involved in nitrite ammonification, reveal substantial structural similarity in the polypeptide chain surrounding the heme core environment. The structural determinants of these heme-packing motifs extend to the buried water molecules that hydrogen bond to the histidine ligands to the heme iron. In the original structure determination of a tetragonal crystal form, a cis peptide bond between His129 and Phe130 was identified that appeared to be stabilized by crystal contacts. In the rhombohedral crystal form used in the present high-resolution structure determination, this peptide bond adopts the trans conformation, but with disallowed angles of phi and psi.
Organizational Affiliation:
Division of Chemistry and Chemical Engineering and Howard Hughes Medical Institute, MC 147-75 CH, California Institute of Technology, Pasadena, CA 91125, USA.
