A host protein (La) binds to a unique species of minus-sense leader RNA during replication of vesicular stomatitis virus.

Abstract

Baby hamster kidney cells infected with the minus-strand RNA virus vesicular stomatitis virus (VSV) were found to contain three small viral leader RNA species of the minus sense. The longest minus-strand leader RNA was 54 nucleotides long and was complexed with the host cell La protein that was immunoprecipitated by antisera from patients with systemic lupus ery-*thematosus. The La protein is normally found associated with RNA polymerase Ill transcripts in their unprocessed form. Shorter minus-strand leader RNA species of 45-48 nucleotides were more abundant but were not associated with the La protein. Unlike the plus-strand leader RNA of VSV, the minus-strand leader RNAs were not detected in the nucleus in any form. The minus-strand leader RNAs accumulated gradually throughout the infection and could not be found in association with the viral nucleocapsid protein. The sequence required for La protein binding on the 54-nucleotide-long minus-strand leader is similar to that at the 3' end of the La protein binding-plus-strand leader RNA and, thus, we propose a role for the La protein in the replication of VSV.Vesicular stomatitis virus (VSV) is a minus-strand RNA cytoplasmic virus that packages RNA polymerase in purified virions. The 42S genomic RNA serves as template for five monocistronic, capped, and polyadenylylated mRNAs. Viral RNA polymerase initiates transcription in vivo and in vitro at the 3' end of the genome and sequentially transcribes the genes in the order 3' N-NS-M-G-L 5' (1). In addition, the polymerase also synthesizes a leader RNA from the 3' terminus of the genome. This plus-sense leader RNA has been implicated in the shutoff of host macromolecular synthesis (2, 3) and is transported to the nucleus early in the infection (4). In addition, it may serve as a decision point. for the switch from viral transcription to replication (5). The mechanism by which this switch occurs is unknown. In the process of replication, the virus must synthesize a full-length 42S plus-sense complementary product from the genomic minus-sense RNA. The 42S plus strand in turn serves as template for two kinds of RNA products: full-length minus strands for packaging into progeny particles and short minusstrand leader RNAs. The minus-strand leader RNA may serve as an early decision point for synthesis of the genomic minus strand during replication (5).Several lines of evidence have suggested a role for host cell factors in VSV transcription and replication. Host range mutants of VSV have been isolated that have altered transcriptive properties (6, 7) and extracts from uninfected cells have been found to alter the quality and quantity of in vitro transcription (refs. 8 and 9; unpublished data). The nature of these factors is not understood and whether they interact with the RNA polymerase, the ribonucleoprotein (RNP) template, or the viral transcripts has not been determined. Virus-host interactions affecting transcription may be central to understanding VSV .replication and viral cytopathology.We have recently foun...

Temporal correlation of antibody responses to different epitopes of the human La autoantigen.

“…ecules (9). These RNA species are chiefly products of RNA polymerase III and include 7S RNA, pre-5S RNA, pre-tRNA, 4.5 I RNA, Y RNA, and several viral RNA (10)(11)(12)(13)(14)(15)(16); Ul RNA is also bound by the La protein, although it is transcribed by RNA polymerase 11 (17). The structure of the La protein has been deduced from nucleotide sequencing of genomic and complementary DNA (cDNA) clones (9,(18)(19)(20)(21).…”

Specific Phosphorylated Forms of Glyceraldehyde 3-Phosphate Dehydrogenase Associate with Human Parainfluenza Virus Type 3 and Inhibit Viral Transcription In Vitro

“…Recent studies indicate that the La protein exists in multiple molecular forms (30) and thus may be involved in diverse activities, as reported for GAPDH (17,30,33,37,41). Similar to GAPDH, the La protein also interacts with cisacting RNAs of several viruses, including HPIV3 (11), vesicular stomatitis virus (26,53), rabies virus (25), Sindbis virus (38), poliovirus (31), and human immunodeficiency virus (5). Although the La protein's role in the virus life cycle remains largely unclear, its interaction with poliovirus RNA has been shown to relieve structural constraint during translation.…”

La protein binds the predicted loop structures in the 3′ non-coding region of Japanese encephalitis virus genome: role in virus replication

“…Most La protein is localized in the nucleus, although some is found in the cytoplasm, especially under conditions of cellular stress such as viral infection (Meerovitch et al, 1993). In addition to binding to the NCRs of many RNA viruses, La protein has been shown to bind small viral RNAs such as EpsteinBarr virus-encoded RNAs (Rosa et al, 1981), VA RNAs of adenovirus (Francoeur & Mathews, 1982) and the leader sequence of a unique RNA produced during replication of VSV (Wilusz et al, 1983). Several putative roles have been ascribed to La protein in various processes related to virus replication such as transcription termination (Gottlieb & Steitz, 1989a;Maraia et al, 1994), translation enhancement (Chang et al, 1994;Meerovitch et al, 1993;Svitkin et al, 1994) and viral RNA stabilization (Spangberg et al, 2001).…”

“…Journal of General Virology 90 sequence of a unique RNA produced during replication of VSV (Wilusz et al, 1983). Several putative roles have been ascribed to La protein in various processes related to virus replication such as transcription termination (Gottlieb & Steitz, 1989a;Maraia et al, 1994), translation enhancement (Chang et al, 1994;Meerovitch et al, 1993;Svitkin et al, 1994) and viral RNA stabilization (Spangberg et al, 2001).…”