Oct 10:  Capsid-RNA interaction in a model RNA virus.

Speaker：Peng Ni

Host: Lujian Liao

When: 2013-10-10  10:30

Where: Conference Room 433, School of Life Sciences

Abstract: The nucleocapsid protein (NC) is a small retroviral basic protein containing two zinc fingers and that is involved in several steps of the Human Immunodeficiency Virus-1 (HIV-1) replication cycle such as genome selection, encapsidation, and reverse transcription. In particular, NC possesses a nucleic acid chaperoning activity and is strongly involved in the strand transfers occurring during reverse transcription. The protein possesses a binding preference for single strand nucleic acid sequences located in bulges or loops of the HIV-1 genome either the RNA or DNA forms. Unpaired guanines are the preferred binding substrate of the protein. Besides these binding to single stranded nucleic acids, the protein is able to destabilize nucleic acid secondary structures adjacent to the bound sequences. This latter activity, associated to its ability to mediate nucleic acids aggregation, permit to the protein to behave as a powerful chaperon protein that facilitates annealing of complementary nucleic acid strands. In our works, using nuclear magnetic resonance (NMR) spectroscopy and molecular biology methods, we studied in detail the binding properties of the protein to nucleic acid elements involved in the first strand transfer. The determination of the three-dimensional structure of a new NC-DNA complex and its comparison with the others existing complexes lead us to propose new rules for the NC recognition of nucleic acids.  Additionally 15N NMR spin relaxation measurements allowed us to investigate in detail the internal dynamics of the protein and bring a new comprehension of the respective roles of the two zinc fingers in the chaperoning activity of NC.