The Proapoptotic G41S Mutation to Human Cytochrome c Alters the Heme Electronic Structure and Increases the Electron Self-Exchange Rate.Liptak, M.D., Fagerlund, R.D., Ledgerwood, E.C., Wilbanks, S.M., Bren, K.L.
(2011) J Am Chem Soc 133: 1153-1155
- PubMed: 21192676
- DOI: https://doi.org/10.1021/ja106328k
- Primary Citation of Related Structures:
- PubMed Abstract:
The naturally occurring G41S mutation to human (Hs) cytochrome (cyt) c enhances apoptotic activity based upon previous in vitro and in vivo studies, but the molecular mechanism underlying this enhancement remains unknown. Here, X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and density functional theory (DFT) calculations have been used to identify the structural and electronic differences between wild-type (WT) and G41S Hs cyt c. S41 is part of the hydrogen bonding network for propionate 7 of heme pyrrole ring A in the X-ray structure of G41S Hs cyt c and, compared to WT, G41S Hs cyt c has increased spin density on pyrrole ring C and a faster electron self-exchange rate. DFT calculations illustrate an electronic mechanism where structural changes near ring A can result in electronic changes at ring C. Since ring C is part of the solvent-exposed protein surface, we propose that this heme electronic structure change may ultimately be responsible for the enhanced proapoptotic activity of G41S Hs cyt c.
Department of Chemistry, University of Rochester, Rochester, New York 14627, United States.