Cytochrome c6A is a unique dithio-cytochrome of green algae and plants. It has a very similar core structure to that of bacterial and algal cytochromes c6, but is unable to fulfil the same function of transferring electrons from cytochrome f to Photosystem I. A key feature of cytochrome c6A is that its haem midpoint potential is more than 200 mV below that of cytochrome c6 (Em≈+340 mV) despite both cytochromes having histidine and methionine residues as axial haem-iron ligands. One salient difference between the haem pockets is that a valine residue in cytochrome c6A replaces a highly conserved glutamine residue in cytochrome c6. This difference has been probed using site-directed mutagenesis, X-ray crystallography and protein film voltammetry studies. It has been found that the stereochemistry of the glutamine residue within the haem pocket has a destabilizing effect and is responsible for tuning the haem's midpoint potential by over 100 mV. This large effect may have contributed to the evolution of a new biological function for cytochrome c6A.
Skip Nav Destination
Article navigation
December 2008
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
Conference Article|
November 19 2008
Cytochrome c6A: discovery, structure and properties responsible for its low haem redox potential
Jonathan A.R. Worrall;
Jonathan A.R. Worrall
1
*Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, U.K.
1To whom correspondence should be addressed (email jworrall@essex.ac.uk).
Search for other works by this author on:
Ben F. Luisi;
Ben F. Luisi
†Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, U.K.
Search for other works by this author on:
Beatrix G. Schlarb-Ridley;
Beatrix G. Schlarb-Ridley
†Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, U.K.
Search for other works by this author on:
Derek S. Bendall;
Derek S. Bendall
†Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, U.K.
Search for other works by this author on:
Christopher J. Howe
Christopher J. Howe
†Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, U.K.
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
June 27 2008
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© The Authors Journal compilation © 2008 Biochemical Society
2008
Biochem Soc Trans (2008) 36 (6): 1175–1179.
Article history
Received:
June 27 2008
Citation
Jonathan A.R. Worrall, Ben F. Luisi, Beatrix G. Schlarb-Ridley, Derek S. Bendall, Christopher J. Howe; Cytochrome c6A: discovery, structure and properties responsible for its low haem redox potential. Biochem Soc Trans 1 December 2008; 36 (6): 1175–1179. doi: https://doi.org/10.1042/BST0361175
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Captcha Validation Error. Please try again.