Poster abstracts

Poster number 61 submitted by Meng Sun

Investigating the Interaction between HTLV-2 Matrix and its RNA Packaging Signal

Meng Sun (Department of Chemistry, The Ohio State University), Karin Musier-Forsyth (Department of Chemistry, The Ohio State University)

Abstract:
Retroviral RNA encapsidation involves a recognition event between genomic RNA packaging signals and one or more domains in Gag. The primary packaging signal of deltaretroviruses including BLV, HTLV-1 and HTLV-2 was predicted to be two stem-loop structures, SL1 and SL2, which are located in the 5-UTR region. Previous work showed that mutation of conserved charged residues in the BLV matrix (MA) domain affects virus replication and viral RNA packaging efficiencies. To gain further insight into the role of the MA domain of Gag in directing viral RNA packaging, we examined the interaction of HTLV-2 MA and its putative packaging signal in vitro. We also used mutagenesis to probe the role of conserved charged amino acid residues of MA in aggregating and binding non-specific and specific nucleic acids. Electrophoretic mobility shift assays and fluorescence anisotropy measurements were performed to obtain the binding affinity of MA and its mutants to nucleic acids. In general, HTLV-2 MA displays higher binding affinity to nucleic acids than either HIV-1 MA or HTLV-1 NC. The simultaneous mutation of two basic residues (R47A/K51A) in MA á-helix II, results in a severe binding defect relative to wild-type, whereas single point mutations have more modest effects on binding. In addition, MA binds with similar affinity to single- or double-stranded nucleic acids or stem-loop structures. Taken together, these results are consistent with a direct interaction between HTLV-2 MA and its packaging signal, and this interaction is driven, at least in part, by electrostatic forces.

Keywords: Matrix, packaging, interaction