Molecular dynamics simulation studies on structural and conformational changes in tyrosine-67 nitrated cytochrome c

Abstract

Protein tyrosine nitration is well-established post-translational modification occurring in a number of diseases, viz. neurodegenerative, cardiovascular diseases, ageing, etc. Tyrosine-67 (Tyr-67) nitration of cytochrome c (cyt c) was observed under oxidative stress affecting its structure and electron transfer properties. Hence, in this study, molecular dynamics (MD) simulations were carried out at room temperature to investigate the structural and conformational changes in the nitrated cyt c's. MD results revealed that the bond between FE (Heme-105) and S (Met-80) considerably weakened, radius of gyration, backbone and Cα root-mean-square deviations decreased and hydrogen bonding increased in the nitrated cyt c's relative to wild type (WT) cyt c. Ramachandran plot analysis revealed that N- and C-terminal helices also affected by nitration at CE2 carbon atom. Furthermore, essential dynamics analysis showed that amplitude of concerted motion decreased in the nitrated cyt c's, perhaps due to the increase in the hydrogen bonding interaction. Taken together, the structural and conformational changes in the active site Tyr-67 nitrated cyt c may have implications in the loss of electron/proton transfer and gain of apoptotic properties.

Keywords:

• nitrotyrosine
• peroxynitrite
• cyt c nitration
• apoptosis
• MD simulation
• essential dynamics

Acknowledgements

Thanks are due to the VHNSN College Managing Board for facilities and University Grants Commission (F. no. 39-690/2010), New Delhi, for financial support.