Solution Structure of a Hydrocarbon Stapled Peptide Inhibitor in Complex with Monomeric C-terminal Domain of HIV-1 Capsid

Shibani Bhattacharya,Hongtao Zhang,Asim K Debnath,David Cowburn

doi:10.1074/jbc.c800048200

Abstract

The human immunodeficiency virus type 1 (HIV-1) capsid protein plays a critical role in virus core particle assembly and is an important target for novel therapeutic strategies. In a previous study, we characterized the binding affinity of a hydrocarbon stapled helical peptide, NYAD-1, for the capsid protein (K(d) approximately 1 mum) and demonstrated its ability to penetrate the cell membrane (Zhang, H., Zhao, Q., Bhattacharya, S., Waheed, A. A., Tong, X., Hong, A., Heck, S., Goger, M., Cowburn, D., Freed, E. O., and Debnath, A. K. (2008) J. Mol. Biol. 378, 565-580). In cell-based assays, NYAD-1 colocalized with the Gag polyprotein during traffic to the plasma membrane and disrupted the formation of mature and immature virus particles in vitro systems. Here, we complement the cellular and biochemical data with structural characterization of the interactions between the capsid and a soluble peptide analogue, NYAD-13. Solution NMR methods were used to determine a high resolution structure of the complex between the inhibitor and a monomeric form of the C-terminal domain of the capsid protein (mCA-CTD). The intermolecular interactions are mediated by the packing of hydrophobic side chains at the buried interface and unperturbed by the presence of the olefinic chain on the solvent-exposed surface of the peptide. The results of the structural analysis provide valuable insight into the determinants for high affinity and selective inhibitors for HIV-1 particle assembly.

Highlights

As we gain further insight into the structural biology of the virus particle itself and the mechanism of its assembly from the gag polyprotein, the latter has emerged as an important new target for drug development [2]
The dimeric capsid protein consists of N- and C-terminal domains that are flexibly linked in each monomer, and dimerization is mediated by the C-terminal domain
The formation of the hexamer is mediated by the N-terminal domain of the capsid, and the hexameric rings are bridged by the C-terminal dimerization domain [3, 4]

Summary

Introduction

As we gain further insight into the structural biology of the virus particle itself and the mechanism of its assembly from the gag polyprotein, the latter has emerged as an important new target for drug development [2]. We characterized the binding affinity of a hydrocarbon stapled helical peptide, NYAD-1, for the capsid protein (Kd ϳ 1 ␮M) and demonstrated its ability to penetrate the cell membrane

Results

Conclusion