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J Biol Chem. 2018 Oct 19;293(42):16261-16276. doi: 10.1074/jbc.RA118.005531. Epub 2018 Sep 14.

Human T-cell leukemia virus type 1 Gag domains have distinct RNA-binding specificities with implications for RNA packaging and dimerization.

Author information

1
From the Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus Ohio 43210 and.
2
Institute for Molecular Virology.
3
Molecular, Cellular, Developmental Biology and Genetics Graduate Program, and.
4
Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455.
5
From the Department of Chemistry and Biochemistry, Center for Retrovirus Research, and Center for RNA Biology, The Ohio State University, Columbus Ohio 43210 and musier@chemistry.ohio-state.edu.

Abstract

Human T-cell leukemia virus type 1 (HTLV-1) is the first retrovirus that has conclusively been shown to cause human diseases. In HIV-1, specific interactions between the nucleocapsid (NC) domain of the Gag protein and genomic RNA (gRNA) mediate gRNA dimerization and selective packaging; however, the mechanism for gRNA packaging in HTLV-1, a deltaretrovirus, is unclear. In other deltaretroviruses, the matrix (MA) and NC domains of Gag are both involved in gRNA packaging, but MA binds nucleic acids with higher affinity and has more robust chaperone activity, suggesting that this domain may play a primary role. Here, we show that the MA domain of HTLV-1, but not the NC domain, binds short hairpin RNAs derived from the putative gRNA packaging signal. RNA probing of the HTLV-1 5' leader and cross-linking studies revealed that the primer-binding site and a region within the putative packaging signal form stable hairpins that interact with MA. In addition to a previously identified palindromic dimerization initiation site (DIS), we identified a new DIS in HTLV-1 gRNA and found that both palindromic sequences bind specifically the NC domain. Surprisingly, a mutant partially defective in dimer formation in vitro exhibited a significant increase in RNA packaging into HTLV-1-like particles, suggesting that efficient RNA dimerization may not be strictly required for RNA packaging in HTLV-1. Moreover, the lifecycle of HTLV-1 and other deltaretroviruses may be characterized by NC and MA functions that are distinct from those of the corresponding HIV-1 proteins, but together provide the functions required for viral replication.

KEYWORDS:

Gag; HTLV-1; RNA binding protein; RNA dimerization; RNA folding; RNA structure; matrix domain; nucleocapsid; retrovirus; viral replication

PMID:
30217825
PMCID:
PMC6200928
[Available on 2019-10-19]
DOI:
10.1074/jbc.RA118.005531
[Indexed for MEDLINE]

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