title: Functional Equivalence of Retroviral MA Domains in Facilitating Psi RNA Binding Specificity by Gag.
abstract: Retroviruses specifically package full-length, dimeric genomic RNA (gRNA) even in the presence of a vast excess of cellular RNA. The "psi" (Ψ) element within the 5'-untranslated region (5'UTR) of gRNA is critical for packaging through interaction with the nucleocapsid (NC) domain of Gag. However, in vitro Gag binding affinity for Ψ versus non-Ψ RNAs is not significantly different. Previous salt-titration binding assays revealed that human immunodeficiency virus type 1 (HIV-1) Gag bound to Ψ RNA with high specificity and relatively few charge interactions, whereas binding to non-Ψ RNA was less specific and involved more electrostatic interactions. The NC domain was critical for specific Ψ binding, but surprisingly, a Gag mutant lacking the matrix (MA) domain was less effective at discriminating Ψ from non-Ψ RNA. We now find that Rous sarcoma virus (RSV) Gag also effectively discriminates RSV Ψ from non-Ψ RNA in a MA-dependent manner. Interestingly, Gag chimeras, wherein the HIV-1 and RSV MA domains were swapped, maintained high binding specificity to cognate Ψ RNAs. Using Ψ RNA mutant constructs, determinants responsible for promoting high Gag binding specificity were identified in both systems. Taken together, these studies reveal the functional equivalence of HIV-1 and RSV MA domains in facilitating Ψ RNA selectivity by Gag, as well as Ψ elements that promote this selectivity.
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Center for Retroviral Research, and Center for RNA Biology, Columbus, OH 43210, USA. rye.10@osu.edu.
authors.forename: Tiffiny
authors.initials: T
authors.lastname: Rye-McCurdy
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Center for Retroviral Research, and Center for RNA Biology, Columbus, OH 43210, USA. olson.249@osu.edu.
authors.forename: Erik D
authors.initials: ED
authors.lastname: Olson
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Center for Retroviral Research, and Center for RNA Biology, Columbus, OH 43210, USA. liu.4982@buckeyemail.osu.edu.
authors.forename: Shuohui
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Center for Retroviral Research, and Center for RNA Biology, Columbus, OH 43210, USA. binkley.94@osu.edu.
authors.forename: Christiana
authors.initials: C
authors.lastname: Binkley
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Center for Retroviral Research, and Center for RNA Biology, Columbus, OH 43210, USA. reyes.313@buckeyemail.osu.edu.
authors.forename: Joshua-Paolo
authors.initials: JP
authors.lastname: Reyes
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Center for Retroviral Research, and Center for RNA Biology, Columbus, OH 43210, USA. thompson.2255@buckeyemail.osu.edu.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Thompson
authors.affiliation: Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA. jmf27@psu.edu.
authors.forename: John M
authors.initials: JM
authors.lastname: Flanagan
authors.affiliation: Departments of Medicine and Microbiology and Immunology, Division of Infectious Diseases and Epidemiology, Penn State College of Medicine, Hershey, PA 17033, USA. lparent@psu.edu.
authors.forename: Leslie J
authors.initials: LJ
authors.lastname: Parent
authors.affiliation: Department of Chemistry and Biochemistry, The Ohio State University, Center for Retroviral Research, and Center for RNA Biology, Columbus, OH 43210, USA. musier-forsyth.1@osu.edu.
authors.forename: Karin
authors.initials: K
authors.lastname: Musier-Forsyth
keywords: Gag; Psi RNA (Ψ RNA); Rous sarcoma virus (RSV); human immunodeficiency virus type 1 (HIV-1); matrix (MA); nucleocapsid (NC)