Research article

Endophilins interact with Moloney murine leukemia virus Gag and modulate virion production

Margaret Q Wang¹, Wankee Kim⁴, Guangxia Gao⁵, Ted A Torrey⁶, Herbert C Morse III⁶, Pietro De Camilli⁷ and Stephen P Goff^1,2,3

¹Department of Microbiology, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA

²Howard Hughes Medical Institute, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA

³Department of Biochemistry and Molecular Biophysics, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA

⁴Institute for Medical Sciences, Ajou University, South Korea

⁵Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, China

⁶Laboratory of Immunopathology, NIAID, NIH, Rockville, MD 20852, USA

⁷Howard Hughes Medical Institute and Department of Cell Biology, Yale University, New Haven, CT 06510, USA

author email corresponding author email

Journal of Biology 2003, 3:4doi:10.1186/1475-4924-3-4

Published:	4 December 2003

Abstract

Background

The retroviral Gag protein is the central player in the process of virion assembly at the plasma membrane, and is sufficient to induce the formation and release of virus-like particles. Recent evidence suggests that Gag may co-opt the host cell's endocytic machinery to facilitate retroviral assembly and release.

Results

A search for novel partners interacting with the Gag protein of the Moloney murine leukemia virus (Mo-MuLV) via the yeast two-hybrid protein-protein interaction assay resulted in the identification of endophilin 2, a component of the machinery involved in clathrin-mediated endocytosis. We demonstrate that endophilin interacts with the matrix or MA domain of the Gag protein of Mo-MuLV, but not of human immunodeficiency virus, HIV. Both exogenously expressed and endogenous endophilin are incorporated into Mo-MuLV viral particles. Titration experiments suggest that the binding sites for inclusion of endophilin into viral particles are limited and saturable. Knock-down of endophilin with small interfering RNA (siRNA) had no effect on virion production, but overexpression of endophilin and, to a lesser extent, of several fragments of the protein, result in inhibition of Mo-MuLV virion production, but not of HIV virion production.

Conclusions

This study shows that endophilins interact with Mo-MuLV Gag and affect virion production. The findings imply that endophilin is another component of the large complex that is hijacked by retroviruses to promote virion production.