PDBsum entry 3m97

Electron transport

PDB id: 3m97

Contents

Protein chain

118 a.a. *

Ligands

HEC

Metals

_ZN ×4

Waters ×227

* Residue conservation analysis

PDB id:

3m97

Name:

Electron transport

Title:

Structure of the soluble domain of cytochrome c552 with its flexible linker segment from paracoccus denitrificans

Structure:

CytochromE C-552. Chain: x. Fragment: soluble domain with flexible linker segment (unp residues 38-176). Synonym: cytochrome c552. Engineered: yes

Source:

Paracoccus denitrificans. Organism_taxid: 266. Gene: cycm. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.33Å R-factor: 0.201 R-free: 0.229

Authors:

C.Rajendran,U.Ermler,B.Ludwig,H.Michel

Key ref:

C.Rajendran et al. (2010). Structure at 1.5 A resolution of cytochrome c(552) with its flexible linker segment, a membrane-anchored protein from Paracoccus denitrificans. Acta Crystallogr D Biol Crystallogr, 66, 850-854. PubMed id: 20606266

Date:

20-Mar-10 Release date: 21-Jul-10

Protein chain

P54820  (CY552_PARDE) -  Cytochrome c-552 from Paracoccus denitrificans

Seq: 176 a.a.

Struc: 118 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

Acta Crystallogr D Biol Crystallogr 66:850-854 (2010)

PubMed id: 20606266

Structure at 1.5 A resolution of cytochrome c(552) with its flexible linker segment, a membrane-anchored protein from Paracoccus denitrificans.

C.Rajendran, U.Ermler, B.Ludwig, H.Michel.

ABSTRACT

Electron transfer (ET) between the large membrane-integral redox complexes in the terminal part of the respiratory chain is mediated either by a soluble c-type cytochrome, as in mitochondria, or by a membrane-anchored cytochrome c, as described for the ET chain of the bacterium Paracoccus denitrificans. Here, the structure of cytochrome c(552) from P. denitrificans with the linker segment that attaches the globular domain to the membrane anchor is presented. Cytochrome c(552) including the linker segment was crystallized and its structure was determined by molecular replacement. The structural features provide functionally important information. The prediction of the flexibility of the linker region [Berry & Trumpower (1985), J. Biol. Chem. 260, 2458-2467] was confirmed by our crystal structure. The N-terminal region from residues 13 to 31 is characterized by poor electron density, which is compatible with high mobility of this region. This result indicates that this region is highly flexible, which is functionally important for this protein to shuttle electrons between complexes III and IV in the respiratory chain. Zinc present in the crystallization buffer played a key role in the successful crystallization of this protein. It provided rigidity to the long negatively charged flexible loop by coordinating negatively charged residues from two different molecules and by enhancing the crystal contacts.