title: The "complex" RNA post-transcriptional element of a "simple" retrovirus.
abstract: Replication of retroviruses and transposition of endogenous retroelements exploits a unique mechanism of post-transcriptional regulation as a means of exporting their incompletely-spliced mRNAs (which serve as both the genomic RNA and the template for protein synthesis). Following discovery of the Rev response element (RRE) that mediates nucleocytoplasmic export of the full-length and singly-spliced human immunodeficiency virus type 1 (HIV-1) genome, equivalentcis-acting regulatory elements have been characterized for both complex and simple retroviruses and retroelements, together with the obligate viral and host proteins with which they interact. The exception to this is the gammaretrovirus family of simple retroviruses, exemplified by reticuloendotheliosis virus (REV), murine leukemia virus (MLV) and xenotropic MLV-related retrovirus (XMRV). In this commentary, we discuss our recent data that reported structural and functional data on the MLV/XMRV post-transcriptional regulatory element (designated the PTE). The PTE was characterized by a highly-structured region of multiple stem-loops (SL1 - SL7) overlapping theproand 5' portion of thepolopen reading frames, comprising a bipartite export signal whose structures are separated by ∼1400 nt. In addition, structural probing suggested that SL3 nucleotides were involved in pseudoknot formation. These data, when compared with RNA transport elements of complex retroviruses (HIV) and simple murine retrotransposons (musD), collectively present an emerging picture that long-range tertiary interactions are critical mediators of their biological function.
authors.affiliation: Institute of Bioorganic Chemistry; Polish Academy of Sciences ; Poznan, Poland.
authors.forename: Katarzyna J
authors.initials: KJ
authors.lastname: Purzycka
authors.affiliation: Human Retrovirus; Pathogenesis Section; Vaccine Branch ; Frederick, MD USA.
authors.forename: Guy R
authors.initials: GR
authors.lastname: Pilkington
authors.affiliation: Human Retrovirus; Pathogenesis Section; Vaccine Branch ; Frederick, MD USA.
authors.forename: Barbara K
authors.initials: BK
authors.lastname: Felber
authors.affiliation: RT Biochemistry Section; Basic Research Laboratory; National Cancer Institute Frederick ; Frederick, MD USA.
authors.forename: Stuart F J
authors.initials: SF
authors.lastname: Le Grice
keywords: RNA transport element; gammaretrovirus; long-range interactions