Identification of a new transcriptional initiation site and the corresponding functional gene 2b in the murine coronavirus RNA genome

C. K. Shieh, H. J. Lee, K. Yokomori, N. La Monica, Shinji Makino, M. M C Lai

Research output: Contribution to journalArticle

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Abstract

We have previously shown that some strains of the murine coronavirus mouse hepatitis virus (MHV) synthesize an additional mRNA species (mRNA 2b, previously called mRNA 2a) with a size intermediate between that of mRNAs 2 and 3, suggesting the presence of an optimal transcriptional initiation site. This transcriptional start is dependent on the leader sequence of the virus strains. To study the mechanism of coronavirus transcriptional regulation, we have cloned and sequenced the region of the viral genome corresponding to the 5' unique coding region of mRNA 2 of the JHM strain of MHV. In addition to the open reading frame (ORF) predicted to encode the viral nonstructural protein p30, a second complete ORF, with the potential to encode a 439-amino-acid polypeptide, was discovered. The transcriptional initiation sites of both mRNA 2a (formerly called mRNA 2) and mRNA 2b were determined by primer extension studies and RNA sequencing. The data indicated that transcription of mRNA 2a initiated at a site, UCUAUAC, that resembled the consensus intergenic sequence. In contrast, the start signal of the optional mRNA 2b, UAAUAAAC, deviated from the consensus sequence. mRNA 2b is a functional mRNA, as shown by in vitro translation studies of mRNA and ORF 2b and by the detection of an additional viral structural protein, gp65, in the JHM strain that synthesized this mRNA. Although the A59 strain of MHV was found to retain ORF 2b, it lacked the correct transcriptional and translational start signals for this gene. This study has therefore identified an optional gene product for murine coronaviruses and provided insights into the mechanism of regulation of MHV RNA transcription.

Original languageEnglish (US)
Pages (from-to)3729-3736
Number of pages8
JournalJournal of Virology
Volume63
Issue number9
StatePublished - 1989
Externally publishedYes

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Murine coronavirus
Murine hepatitis virus
Coronavirus
Genome
RNA
open reading frames
Messenger RNA
genome
Genes
genes
transcription (genetics)
Open Reading Frames
Coronavirinae
consensus sequence
viral proteins
structural proteins
intergenic DNA
translation (genetics)
Consensus Sequence
polypeptides

ASJC Scopus subject areas

  • Immunology

Cite this

Identification of a new transcriptional initiation site and the corresponding functional gene 2b in the murine coronavirus RNA genome. / Shieh, C. K.; Lee, H. J.; Yokomori, K.; La Monica, N.; Makino, Shinji; Lai, M. M C.

In: Journal of Virology, Vol. 63, No. 9, 1989, p. 3729-3736.

Research output: Contribution to journalArticle

Shieh, C. K. ; Lee, H. J. ; Yokomori, K. ; La Monica, N. ; Makino, Shinji ; Lai, M. M C. / Identification of a new transcriptional initiation site and the corresponding functional gene 2b in the murine coronavirus RNA genome. In: Journal of Virology. 1989 ; Vol. 63, No. 9. pp. 3729-3736.
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