Molecular insights on the conformational dynamics of a P76C mutant of human cytochrome c and the enhancement on its peroxidase activity
Issued Date
2022-02-15
Resource Type
ISSN
00039861
eISSN
10960384
Scopus ID
2-s2.0-85121789780
Pubmed ID
34954215
Journal Title
Archives of Biochemistry and Biophysics
Volume
716
Rights Holder(s)
SCOPUS
Bibliographic Citation
Archives of Biochemistry and Biophysics Vol.716 (2022)
Suggested Citation
Samsri S., Prasertsuk P., Nutho B., Pornsuwan S. Molecular insights on the conformational dynamics of a P76C mutant of human cytochrome c and the enhancement on its peroxidase activity. Archives of Biochemistry and Biophysics Vol.716 (2022). doi:10.1016/j.abb.2021.109112 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/83825
Title
Molecular insights on the conformational dynamics of a P76C mutant of human cytochrome c and the enhancement on its peroxidase activity
Author(s)
Author's Affiliation
Other Contributor(s)
Abstract
In apoptotic pathway, the interaction of Cytochrome c (Cytc) with cardiolipin in vivo is a key process to induce peroxidase activity of Cytc and trigger the release of Cytc in the inner mitochondria into cytosol. The peroxidase active form of Cytc occurs due to local conformational changes that support the opening of the heme crevice and the loss of an axial ligand between Met80 and heme Fe. Structural adjustments at the Ω-loop segments of Cytc are required for such process. To study the role of the distal Ω-loop segments comprising residues 71–85 in human Cytc (hCytc), we investigated a cysteine mutation at Pro76, one of the highly conserved residues in this loop. The effect of P76C mutant was explored by the combination of experimental characterizations and molecular dynamics (MD) simulations. The peroxidase activity of the P76C mutant was found to be significantly increased by ∼13 folds relative to the wild type. Experimental data on global denaturation, alkaline transition, heme bleaching, and spin-labeling Electron Spin Resonance were in good agreement with the enhancement of peroxidase activity. The MD results of hCytc in the hexacoordinate form suggest the important changes in P76C mutant occurred due to the unfolding at the central Ω-loop (residues 40–57), and the weakening of H-bond between Tyr67 and Met80. Whereas the experimental data implied that the P76C mutant tend to be in equilibrium between the pentacoordinate and hexacoordinate forms, the MD and experimental information are complementary and were used to support the mechanisms of peroxidase active form of hCytc.