Interrelationship between Cytoplasmic Retroviral Gag Concentration and Gag-Membrane Association

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• 作者：Keir H. Fogarty¹ ; ² ; ³ ; Serkan Berk¹ ; ⁴ ; Iwen F. Grigsby¹ ; ² ; Yan Chen¹ ; ³ ; Louis M. Mansky¹ ; ² ; ⁵ ; ^{mansky@umn.edu" class="auth_mail} ; Joachim D. Mueller¹ ; ³ ; ⁴ ; ^{mueller@physics.umn.edu" class="auth_mail}
• 关键词：HTLV-1 ; human T-cell leukemia virus type 1 ; HIV-1 ; human immunodeficiency virus type 1 ; dcz-FFS ; dual-color ; z-scan fluorescence fluctuation spectroscopy ; TIRF ; total internal reflection fluorescence ; VLP ; virus-like particle ; FFS ; fluorescence fluctuation spectroscopy ; wt ; wild-type
• 刊名：Journal of Molecular Biology
• 出版年：3 April, 2014
• 年：2014
• 卷：426
• 期：7
• 页码：1611-1624
• 全文大小：1106 K

文摘

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.