Identification of Pr78Gag Binding Sites on the Mason-Pfizer Monkey Virus Genomic RNA Packaging Determinants

J Mol Biol. 2021 May 14;433(10):166923. doi: 10.1016/j.jmb.2021.166923. Epub 2021 Mar 11.

Abstract

How retroviral Gag proteins recognize the packaging signals (Psi) on their genomic RNA (gRNA) is a key question that we addressed here using Mason-Pfizer monkey virus (MPMV) as a model system by combining band-shift assays and footprinting experiments. Our data show that Pr78Gag selects gRNA against spliced viral RNA by simultaneously binding to two single stranded loops on the MPMV Psi RNA: (1) a large purine loop (ssPurines), and (2) a loop which partially overlaps with a mostly base-paired purine repeat (bpPurines) and extends into a GU-rich binding motif. Importantly, this second Gag binding site is located immediately downstream of the major splice donor (mSD) and is thus absent from the spliced viral RNAs. Identifying elements crucial for MPMV gRNA packaging should help in understanding not only the mechanism of virion assembly by retroviruses, but also facilitate construction of safer retroviral vectors for human gene therapy.

Keywords: Footprinting; Gag-RNA interactions; Purines; Retroviruses; hSHAPE.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Pairing
  • Base Sequence
  • Binding Sites
  • Electrophoretic Mobility Shift Assay
  • Gene Expression Regulation, Viral
  • Gene Products, gag / chemistry*
  • Gene Products, gag / genetics
  • Gene Products, gag / metabolism
  • Guanine / chemistry*
  • Guanine / metabolism
  • Host-Pathogen Interactions
  • Mason-Pfizer monkey virus / chemistry*
  • Mason-Pfizer monkey virus / genetics
  • Mason-Pfizer monkey virus / metabolism
  • Nucleic Acid Conformation
  • Papio
  • Protein Binding
  • Protein Conformation
  • Protein Footprinting
  • RNA, Viral / chemistry*
  • RNA, Viral / genetics
  • RNA, Viral / metabolism
  • Signal Transduction
  • Uracil / chemistry*
  • Uracil / metabolism

Substances

  • Gene Products, gag
  • RNA, Viral
  • Uracil
  • Guanine