Poster abstracts
Poster number 52 submitted by Keerthi Gottipati
Structural Basis of Nuclear Export of HIV-1 RNA Mediated by the Rev Response Element
Keerthi Gottipati (Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN), Jerricho Tipo (Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX), Kay H Choi (Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN)
Abstract:
Viral genomic RNA not only codes for proteins but also acts as a regulatory element during virus replication and pathogenesis. While the primary RNA sequence determines virus protein structure and function, the secondary and tertiary structure of RNA are critical to its role as a regulatory element. Human immunodeficiency virus (HIV) integrates the genome into host DNA in the nucleus, and viral RNA messages are exported to cytoplasm for protein expression and genome packaging. This cytoplasmic export of viral RNA is mediated by a specific RNA-protein interaction between the HIV Rev (Regulator of viral expression) protein and the Rev response element (RRE) RNA. Although structures of Rev protein and Rev bound to a short RNA (stem IIb in RRE) have been determined, the architecture of the Rev-RRE multimeric complex involving Rev homo-oligomers and full-length RRE is unknown. Using a combination of tRNA scaffold-based RNA expression, Fab-assisted cryo-electron microscopy (cryo-EM) and X-ray crystallography we are studying the structure of full-length HIV RRE RNA and RRE in complex with Rev. We independently expressed full length RRE (237 nt) and RRE stem-II recombinantly with a tRNA-scaffold. We report the high-resolution molecular structure of Stem-II of RRE and a cryo-EM reconstruction of the full-length RRE. We describe the high affinity binding site of RRE at the 3-way junction of stem-II, the role of the stem-loop structure in initial Rev binding and dimerization. The cryo-EM reconstruction of full-length RRE provides further insight into the arrangement of stem-II with respect to Stem-I (the 2nd binding site of Rev) and the role of the RNA structure in facilitating oligomerization and higher order complex formation between Rev and RRE.
Keywords: Cryo-EM, Structure, HIV-1 RRE