Paramyxovirus mRNA editing leads to G deletions as well as insertions.

Abstract

Paramyxoviruses are thought to edit their P gene mRNAs co‐transcriptionally, by a mechanism in which the polymerase stutters and reads the same template base more than once. Sendai virus (SeV) and bovine parainfluenza virus type 3 (bPIV3) are closely related viruses, but SeV edits its P gene mRNA with the insertion of a single G residue (at approximately 50% frequency) within the sequence 5′ A6G3, whereas bPIV3 inserts 1 to approximately 6 Gs at roughly equal frequency within the sequence 5′ A6G4. When SeV synthetic mini‐genomes containing either SeV or bPIV3 P gene editing cassettes are expressed from cDNA in cells which are also transfected with the SeV NP, P and L genes, the virus‐specific editing patterns were reproduced. Since the bPIV3 editing pattern was reproduced in a system that is otherwise completely SeV, this suggests that all the information for the virus‐specific editing patterns is due to the RNA sequence itself. Unexpectedly, the length of the template C run was found to be critical, even though it varies from 3 to 7 nucleotides in length in different viruses. Expanding this template C run first led to attenuation of the insertion phenotype, and then to deletions rather than insertions. A stuttering or slippage model to account for these events has been further refined to include a pressure which displaces the nascent strand in a given direction once it has disengaged from the template, and the similarities of this model to those which account for readthrough of cellular RNA polymerase transcription blocks are discussed.

RNA editing-like phenomenon in paramyxovirus V gene mRNA observed in insect cells infected with a recombinant baculovirus.

“…In the case of explanation (i), since the frequency of deletions or insertions in AcP2P10G viral DNA clones was statistically lower than that in AcP2P10G mRNA clones (Table 1), it is unlikely that clones with deletions or insertions were generated by errors of Taq polymerase or reverse transcriptase. Although only insertions of G residues into the editing site of hPIV2 have been reported (Ohgimoto et al, 1990 ;Southern et al, 1990), deletions as well as the insertion of G residues have been reported as a result of RNA editing in bovine parainfluenza virus type 3 and Sendai virus (Jacques et al, 1994). Our observations are consistent with these results, in that both deletions and insertions were detected.…”

“…In related paramyxoviruses, it has been shown that the P protein is required, in cooperation with the L protein, for viral RNA synthesis (Curran et al, 1993 ;Deshpande & Portner, 1985 ;Hamaguchi et al, 1983 ;Horikami et al, 1992). The Cterminal sequence of the V protein is conserved in paramyxoviruses (Thomas et al, 1988) and contains conserved cysteine residues in a motif that is homologous to the zinc- finger domains that have been identified in many transcription factors and nucleic acid-binding proteins (Jacques et al, 1994). A recent report showed that the V protein is required for pathogenesis of the virus (Kato et al, 1997).…”

Paramyxovirus evasion of innate immunity: Diverse strategies for common targets

“…This causes a +1 or +2 frameshift in the downstream ORF [10][11][12] which results in the generation of two or three distinct proteins (P, V and W/D/I), which have common N-terminal sequences but unique C-termini ( Figure 1B). A comparable editing process is used by Ebolavirus of the Filovirus family to produce isoforms from its G gene [13] .…”

Genetic manipulation of non-segmented negative-strand RNA viruses

“…This was aimed at the elucidation of cis-and trans-acting transcription factors and involved promoter mutagenesis (Engelhorn et al, 1993;Kfilin et al, 1994;Calain & Roux, 1995;Pattnaik et al, 1995;Wertz et al, 1995;Yu et al, 1995) as well as the analysis of particular properties of the virus polymerases (Jacques et al, 1994;Schnell & Conzelmann, 1996) and the virus assembly process (Kaptur et al, 1995;Mebatsion et al, 1995;Stillman et al, 1995). The approach appears to be applicable to most of the negative-strand RNA viruses, including the segmented bunyaviruses (Dunn et al, 1995;Lopez et al, 1995).…”