PDBsum entry 1ofw

Electron transport

PDB id: 1ofw

Contents

Protein chains

293 a.a. *

Ligands

HEC ×18

GOL ×4

ACT

Waters ×641

* Residue conservation analysis

PDB id:

1ofw

Name:

Electron transport

Title:

Three dimensional structure of the oxidized form of nine heme cytochromE C at ph 7.5

Structure:

Nine-heme cytochromE C. Chain: a, b. Synonym: 9hcc

Source:

Desulfovibrio desulfuricans. Organism_taxid: 876. Atcc: 27774

Biol. unit:

Monomer (from PDB file)

Resolution:

1.50Å R-factor: 0.171 R-free: 0.207

Authors:

I.Bento,V.H.Teixeira,A.M.Baptista,C.M.Soares,P.M.Matias,M.A.Carrondo

Key ref:

I.Bento et al. (2003). Redox-Bohr and other cooperativity effects in the nine-heme cytochrome C from Desulfovibrio desulfuricans ATCC 27774: crystallographic and modeling studies. J Biol Chem, 278, 36455-36469. PubMed id: 12750363 DOI: 10.1074/jbc.M301745200

Date:

22-Apr-03 Release date: 18-Sep-03

Protein chains

Q9RN68  (CYC9_DESDA) -  Nine-heme cytochrome c from Desulfovibrio desulfuricans (strain ATCC 27774 / DSM 6949 / MB)

Seq: 326 a.a.

Struc: 293 a.a.

DOI no: 10.1074/jbc.M301745200

J Biol Chem 278:36455-36469 (2003)

PubMed id: 12750363

Redox-Bohr and other cooperativity effects in the nine-heme cytochrome C from Desulfovibrio desulfuricans ATCC 27774: crystallographic and modeling studies.

I.Bento, V.H.Teixeira, A.M.Baptista, C.M.Soares, P.M.Matias, M.A.Carrondo.

ABSTRACT

The nine-heme cytochrome c is a monomeric multiheme cytochrome found in Desulfovibrio desulfuricans ATCC 27774. The polypeptide chain comprises 296 residues and wraps around nine hemes of type c. It is believed to take part in the periplasmic assembly of proteins involved in the mechanism of hydrogen cycling, receiving electrons from the tetraheme cytochrome c3. With the purpose of understanding the molecular basis of electron transfer processes in this cytochrome, we have determined the crystal structures of its oxidized and reduced forms at pH 7.5 and performed theoretical calculations of the binding equilibrium of protons and electrons in these structures. This integrated study allowed us to observe that the reduction process induced relevant conformational changes in several residues, as well as protonation changes in some protonatable residues. In particular, the surroundings of hemes I and IV constitute two areas of special interest. In addition, we were able to ascertain the groups involved in the redox-Bohr effect present in this cytochrome and the conformational changes that may underlie the redox-cooperativity effects on different hemes. Furthermore, the thermodynamic simulations provide evidence that the N- and C-terminal domains function in an independent manner, with the hemes belonging to the N-terminal domain showing, in general, a lower redox potential than those found in the C-terminal domain. In this way, electrons captured by the N-terminal domain could easily flow to the C-terminal domain, allowing the former to capture more electrons. A notable exception is heme IX, which has low redox potential and could serve as the exit path for electrons toward other proteins in the electron transfer pathway.

Selected figure(s)

Figure 4.
FIG. 4. Detailed view of heme I and its surroundings. a, oxidized form at pH 5.5. b, oxidized form at pH 7.5. c, reduced form at pH 7.5. Carbon atoms are shown in yellow, oxygen atoms in red, nitrogen atoms in blue, and the iron atom in magenta; the H-bond distances are represented as dashed red lines. Prepared with PyMOL (77). Haem, heme; Prop, propionate.

Figure 5.
FIG. 5. Detailed view of heme IV and its surroundings. a, oxidized form at pH 5.5. b, oxidized form at pH 7.5. c, reduced form at pH 7.5. Carbon atoms are shown in yellow, oxygen atoms in red, nitrogen atoms in blue, and the iron atom in magenta; the H-bond distances are represented as dashed red lines. Prepared with PyMOL (77). Haem, heme; Prop, propionate.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2003, 278, 36455-36469) copyright 2003.

Figures were selected by an automated process.