Structural Mimicry Drives HIV-1 Rev-Mediated HERV-K Expression

JOURNAL OF MOLECULAR BIOLOGY

卷:432

Article

O'Carroll, Ina P.¹  Fan, Lixin²  Kroupa, Tomas³  McShane, Erin K.^1,5  Theodore, Christophe¹  Yates, Elizabeth A.¹  Kondrup, Benjamin¹  Ding, Jienyu⁴  Martin, Tyler S.¹  Rein, Alan³  Wang, Yun-Xing⁴ 

[1] US Naval Acad, Dept Chem, Annapolis, MD 21402 USA

[2] NCI, Basic Sci Program, Frederick Natl Lab Canc Res, SAXS Core Facil, Frederick, MD 21702 USA

[3] NCI, HIV Dynam & Replicat Program, NIH, Frederick, MD 21702 USA

[4] NCI, Prot Nucle Acid Interact Sect, Struct Biophys Lab, NIH, Frederick, MD 21702 USA

[5] Stanford Sch Med, Stanford, CA 94305 USA

关键词: HERV-K;    RcRE;    small-angle X-ray scattering;    atomic force microscopy;    HIV-1 Rev;   

DOI  :  10.1016/j.jmb.2020.11.010

来源: Elsevier

【 摘 要 】

Expression of the Human Endogenous Retrovirus Type K (HERV-K), the youngest and most active HERV, has been associated with various cancers and neurodegenerative diseases. As in all retroviruses, a fraction of HERV-K transcripts is exported from the nucleus in unspliced or incompletely spliced forms to serve as templates for translation of viral proteins. In a fraction of HERV-K loci (Type 2 proviruses), nuclear export of the unspliced HERV-K mRNA appears to be mediated by a cis-acting signal on the mRNA, the RcRE, and the protein Rec-these are analogous to the RRE-Rev system in HIV-1. Interestingly, the HIV-1 Rev protein is able to mediate the nuclear export of the HERV-K RcRE, contributing to elevated HERV-K expression in HIV-infected patients. We aimed to understand the structural basis for HIV Rev-HERV-K RcRE recognition. We examined the conformation of the RcRE RNA in solution using small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). We found that the 433-nt long RcRE can assume folded or extended conformations as observed by AFM. SAXS analysis of a truncated RcRE variant revealed an A-shaped topological structure similar to the one previously reported for the HIV-1 RRE. The effect of the overall topology was examined using several deletion variants. SAXS and biochemical analyses demonstrated that the A shape is necessary for efficient Rev-RcRE complex formation in vitro and nuclear export activity in cell culture. The findings provide insight into the mechanism of HERV-K expression and a structural explanation for HIV-1 Rev-mediated expression of HERV-K in HIV-infected patients. Importance: Expression of the human endogenous retrovirus type K (HERV-K) has been associated with various cancers and autoimmune diseases. Nuclear export of both HIV-1 and HERV-K mRNAs is dependent on the interaction between a small viral protein (Rev in HIV-1 and Rec in HERV-K) and a region on the mRNA (RRE in HIV-1 and RcRE in HERV-K). HIV-1 Rev is able to mediate the nuclear export of RcRE-containing HERV-K mRNAs, which contributes to elevated production of HERV-K proteins in HIV-infected patients. We report the solution conformation of the RcRE RNA-the first threedimensional topological structure for a HERV molecule-and find that the RcRE resembles the HIV-1 nuclear export signal, RRE. The finding reveals the structural basis for the increased HERV-K expression observed in HIV-infected patients. Elevated HERV expression, mediated by HIV infection or other stressors, can have various HERV-related biological consequences. The findings provide structural insight for regulation of HERV-K expression. Published by Elsevier Ltd.

【 授权许可】

Free