On the Selective Packaging of Genomic RNA by HIV-1

Viruses

Sean R. Davis¹  Alan Rein²  Mauricio Comas-Garcia² 

[1] Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA;HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA;

关键词: retroviruses;    retroviral RNA;    virus assembly;    HIV-1;    selective RNA packaging;    genomic RNA;    packaging;    encapsidation;    capsid;    RNA-protein interactions;   

DOI  :  10.3390/v8090246

来源: DOAJ

【 摘 要 】

Like other retroviruses, human immunodeficiency virus type 1 (HIV-1) selectively packages genomic RNA (gRNA) during virus assembly. However, in the absence of the gRNA, cellular messenger RNAs (mRNAs) are packaged. While the gRNA is selected because of its cis-acting packaging signal, the mechanism of this selection is not understood. The affinity of Gag (the viral structural protein) for cellular RNAs at physiological ionic strength is not much higher than that for the gRNA. However, binding to the gRNA is more salt-resistant, implying that it has a higher non-electrostatic component. We have previously studied the spacer 1 (SP1) region of Gag and showed that it can undergo a concentration-dependent conformational transition. We proposed that this transition represents the first step in assembly, i.e., the conversion of Gag to an assembly-ready state. To explain selective packaging of gRNA, we suggest here that binding of Gag to gRNA, with its high non-electrostatic component, triggers this conversion more readily than binding to other RNAs; thus we predict that a Gag–gRNA complex will nucleate particle assembly more efficiently than other Gag–RNA complexes. New data shows that among cellular mRNAs, those with long 3′-untranslated regions (UTR) are selectively packaged. It seems plausible that the 3′-UTR, a stretch of RNA not occupied by ribosomes, offers a favorable binding site for Gag.

【 授权许可】

Unknown