PDBsum entry 1chh

Electron transport(heme protein)

PDB id: 1chh

Contents

Protein chain

108 a.a. *

Ligands

SO4

HEC

Waters ×65

* Residue conservation analysis

PDB id:

1chh

Name:

Electron transport(heme protein)

Title:

Structural studies of the roles of residues 82 and 85 at the interactive face of cytochromE C

Structure:

CytochromE C. Chain: a. Engineered: yes

Source:

Saccharomyces cerevisiae. Baker's yeast. Organism_taxid: 4932

Resolution:

1.97Å R-factor: 0.186

Authors:

T.P.Lo,G.D.Brayer

Key ref:

T.P.Lo et al. (1995). Structural studies of the roles of residues 82 and 85 at the interactive face of cytochrome c. Biochemistry, 34, 163-171. PubMed id: 7819192 DOI: 10.1021/bi00001a020

Date:

01-Jun-94 Release date: 20-Dec-94

Protein chain

P00044  (CYC1_YEAST) -  Cytochrome c isoform 1 from Saccharomyces cerevisiae (strain ATCC 204508 / S288c)

Seq: 109 a.a.

Struc: 108 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

DOI no: 10.1021/bi00001a020

Biochemistry 34:163-171 (1995)

PubMed id: 7819192

Structural studies of the roles of residues 82 and 85 at the interactive face of cytochrome c.

T.P.Lo, J.G.Guillemette, G.V.Louie, M.Smith, G.D.Brayer.

ABSTRACT

A combination of structural, functional, and mutagenic experiments has been used to study the roles of the invariant Phe82 and highly conserved Leu85 residues in cytochrome c, especially with respect to the complexation interface with electron transfer partners and maintenance of the hydrophobic heme pocket. Structural analyses show that the F82Y, L85A, and F82Y/L85A mutant proteins all retain the characteristic cytochrome c fold, but that conformational alterations are introduced in the direct vicinity of the mutation sites. In particular, the additional hydroxyl group of Tyr82 is in direct spatial conflict with the side chain of Leu85 in the F82Y mutant protein, leading to rotation of the side chain of Tyr82 out toward the protein surface. This strain is relieved in the F82Y/L85A mutant protein where the phenyl ring of Tyr82 is accommodated in a conformation comparable to that of the phenylalanine normally present at this location. In addition, the available space vacated by the replacement of Leu85 with an alanine allows for the inclusion of two new internal water molecules, one of which is bound to Tyr82 and the other to Arg13. In contrast, in the L85A mutant protein, no internal water molecules are observed in this exclusively hydrophobic pocket, which is partially filled by shifts in nearby side chains. Overall, the conformational changes observed result from the optimization of side chain packing to reflect the spatial requirements of new side chains, the minimization of both vacant internal space and the solvent exposure of hydrophobic groups, and the attainment of maximal hydrogen bonding between available polar groups.(ABSTRACT TRUNCATED AT 250 WORDS)