PDBsum entry 1i6d

Electron transport

PDB id: 1i6d

Contents

Protein chain

100 a.a. *

Ligands

HEC

* Residue conservation analysis

PDB id:

1i6d

Name:

Electron transport

Title:

Solution structure of the functional domain of paracoccus denitrificans cytochrome c552 in the reduced state

Structure:

Cytochrome c552. Chain: a. Fragment: soluble functional domain. Engineered: yes. Other_details: covalent thioether linkages from heme cofactor to both cys14 and cys17

Source:

Paracoccus denitrificans. Organism_taxid: 266. Strain: pd1235. Cellular_location: periplasm. Gene: cycm. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008. Other_details: heterologous expression

NMR struc:

20 models

Authors:

B.Reincke,C.Perez,P.Pristovsek,C.Luecke,C.Ludwig,F.Loehr,V.V.Rogov, B.Ludwig,H.Rueterjans

Key ref:

B.Reincke et al. (2001). Solution structure and dynamics of the functional domain of Paracoccus denitrificans cytochrome c(552) in both redox states. Biochemistry, 40, 12312-12320. PubMed id: 11591150 DOI: 10.1021/bi010615o

Date:

02-Mar-01 Release date: 17-Oct-01

Protein chain

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

Seq: 176 a.a.

Struc: 100 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1021/bi010615o

Biochemistry 40:12312-12320 (2001)

PubMed id: 11591150

Solution structure and dynamics of the functional domain of Paracoccus denitrificans cytochrome c(552) in both redox states.

B.Reincke, C.Pérez, P.Pristovsek, C.Lücke, C.Ludwig, F.Löhr, V.V.Rogov, B.Ludwig, H.Rüterjans.

ABSTRACT

A soluble and fully functional 10.5 kDa fragment of the 18.2 kDa membrane-bound cytochrome c(552) from Paracoccus denitrificans has been heterologously expressed and (13)C/(15)N-labeled to study the structural features of this protein in both redox states. Well-resolved solution structures of both the reduced and oxidized states have been determined using high-resolution heteronuclear NMR. The overall protein topology consists of two long terminal helices and three shorter helices surrounding the heme moiety. No significant redox-induced structural differences have been observed. (15)N relaxation rates and heteronuclear NOE values were determined at 500 and 600 MHz. Several residues located around the heme moiety display increased backbone mobility in both oxidation states, while helices I, III, and V as well as the two concatenated beta-turns between Leu30 and Arg36 apparently form a less flexible domain within the protein structure. Major redox-state-dependent differences of the internal backbone mobility on the picosecond-nanosecond time scale were not evident. Hydrogen exchange experiments demonstrated that the slow-exchanging amide proton resonances mainly belong to the helices and beta-turns, corresponding to the regions with high order parameters in the dynamics data. Despite this correlation, the backbone amide protons of the oxidized cytochrome c(552) exchange considerably faster with the solvent compared to the reduced protein. Using both differential scanning calorimetry as well as temperature-dependent NMR spectroscopy, a significant difference in the thermostabilities of the two redox states has been observed, with transition temperatures of 349.9 K (76.8 degrees C) for reduced and 307.5 K (34.4 degrees C) for oxidized cytochrome c(552). These results suggest a clearly distinct backbone stability between the two oxidation states.