5TY3

Crystal structure of K72A variant of Human Cytochrome c


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.25 Å
  • R-Value Free: 0.166 
  • R-Value Work: 0.147 

wwPDB Validation 3D Report Full Report


This is version 1.0 of the entry. See complete history

Literature

Effect of a K72A Mutation on the Structure, Stability, Dynamics, and Peroxidase Activity of Human Cytochrome c.

Nold, S.M.Lei, H.Mou, T.C.Bowler, B.E.

(2017) Biochemistry 56: 3358-3368

  • DOI: 10.1021/acs.biochem.7b00342

  • PubMed Abstract: 
  • We test the hypothesis that Lys72 suppresses the intrinsic peroxidase activity of human cytochrome c, as observed previously for yeast iso-1-cytochrome c [McClelland, L. J., et al. (2014) Proc. Natl. Acad. Sci. U. S. A. 111, 6648-6653]. A 1.25 Å X-ra ...

    We test the hypothesis that Lys72 suppresses the intrinsic peroxidase activity of human cytochrome c, as observed previously for yeast iso-1-cytochrome c [McClelland, L. J., et al. (2014) Proc. Natl. Acad. Sci. U. S. A. 111, 6648-6653]. A 1.25 Å X-ray structure of K72A human cytochrome c shows that the mutation minimally affects structure. Guanidine hydrochloride denaturation demonstrates that the K72A mutation increases global stability by 0.5 kcal/mol. The K72A mutation also increases the apparent pKa of the alkaline transition, a measure of the stability of the heme crevice, by 0.5 unit. Consistent with the increase in the apparent pKa, the rate of formation of the dominant alkaline conformer decreases, and this conformer is no longer stabilized by proline isomerization. Peroxidase activity measurements show that the K72A mutation increases kcat by 1.6-4-fold at pH 7-10, an effect larger than that seen for the yeast protein. X-ray structures of wild type and K72A human cytochrome c indicate that direct interactions of Lys72 with the far side of Ω-loop D, which are seen in X-ray structures of horse and yeast cytochrome c and could suppress peroxidase activity, are lacking. Instead, we propose that the stronger effect of the K72A mutation on the peroxidase activity of human versus yeast cytochrome c results from relief of steric interactions between the side chains at positions 72 and 81 (Ile in human vs Ala in yeast), which suppress the dynamics of Ω-loop D necessary for the intrinsic peroxidase activity of cytochrome c.


    Organizational Affiliation

    Department of Chemistry and Biochemistry, University of Montana , Missoula, Montana 59812, United States.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Cytochrome c
A, B
104Homo sapiensMutation(s): 0 
Gene Names: CYCS (CYC)
Find proteins for P99999 (Homo sapiens)
Go to Gene View: CYCS
Go to UniProtKB:  P99999
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A, B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
HEC
Query on HEC

Download SDF File 
Download CCD File 
A, B
HEME C
C34 H34 Fe N4 O4
HXQIYSLZKNYNMH-LJNAALQVSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.25 Å
  • R-Value Free: 0.166 
  • R-Value Work: 0.147 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 56.794α = 90.00
b = 37.902β = 116.79
c = 60.254γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data scaling
PHASERphasing
PHENIXrefinement
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2017-09-06
    Type: Initial release