Interrelationship between cytoplasmic retroviral Gag concentration and Gag-membrane association

Keir H Fogarty; Serkan Berk; Iwen F Grigsby; Yan Chen; Louis M Mansky; Joachim D Mueller

doi:10.1016/j.jmb.2013.11.025

Interrelationship between cytoplasmic retroviral Gag concentration and Gag-membrane association

J Mol Biol. 2014 Apr 3;426(7):1611-24. doi: 10.1016/j.jmb.2013.11.025. Epub 2013 Dec 4.

Authors

Keir H Fogarty¹, Serkan Berk², Iwen F Grigsby³, Yan Chen⁴, Louis M Mansky⁵, Joachim D Mueller⁶

Affiliations

¹ Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA.
² Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
³ Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA.
⁴ Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA.
⁵ Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA; Department of Microbiology, University of Minnesota, Minneapolis, MN 55455, USA. Electronic address: mansky@umn.edu.
⁶ Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA; Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA. Electronic address: mueller@physics.umn.edu.

Abstract

The early events in the retrovirus assembly pathway, particularly the timing and nature of Gag translocation from the site of protein translation to the inner leaflet of the plasma membrane, are poorly understood. We have investigated the interrelationship between cytoplasmic Gag concentration and plasma membrane association using complementary live-cell biophysical fluorescence techniques in real time with both human T-cell leukemia virus type 1 (HTLV-1) and human immunodeficiency virus type 1 (HIV-1) Gag proteins. In particular, dual-color, z-scan fluorescence fluctuation spectroscopy in conjunction with total internal reflection fluorescence and conventional, epi-illumination imaging were utilized. Our results demonstrate that HTLV-1 Gag is capable of membrane targeting and particle assembly at low (i.e., nanomolar) cytoplasmic concentrations and that there is a critical threshold concentration (approaching micromolar) prior to the observation of HIV-1 Gag associated with the plasma membrane. These observations imply fundamental differences between HIV-1 and HTLV-1 Gag trafficking and membrane association.

Keywords: assembly; fluorescence; membrane; oligomerization; retrovirus.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Cell Membrane / metabolism*
Cytoplasm / metabolism*
Gene Products, gag / metabolism*
Human T-lymphotropic virus 1 / metabolism
Retroviridae / metabolism*
gag Gene Products, Human Immunodeficiency Virus / metabolism*

Substances

Gene Products, gag
gag Gene Products, Human Immunodeficiency Virus

Abstract

Publication types

MeSH terms

Substances

Grants and funding