Lack of correlation between Sendai virus P/C mRNA structure and its utilization of two AUG start sites from alternate reading frames: Implications for viral bicistronic mRNAs

Kailash C. Gupta, Etsuro Ono, Xiulong Xu

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The polycistronic P/C mRNA of Sendai virus encodes five proteins (C', P, C, Y1, and Y2) each of which initiates from a distinct start site. Two major proteins, P and C, are expressed in approximately equimolar amounts from two consecutive AUGs in overlapping reading frames. To better understand the mechanism of expression of the C protein from a downstream AUG, site-directed mutants of the P/C mRNA were created and expressed in COS1 cells. The secondary structure of the mRNA was examined to determine whether the mRNA structure played any role in the synthesis of the C protein. Our results ruled out any significant involvement of the 5' UTR, sequence contexts, secondary structure, distance between the start sites, and sequences downstream to the C-AUG. However, they are consistent with the concept that the synthesis of the C protein is primarily dependent on the orientation of its reading frame, i.e., + 1 in relation to the upstream P reading frame. The downstream reading frame was translated poorly when it occurred in +2 orientation in relation to the upstream reading frame. Interestingly, all the known functional bicistronic mRNAs with overlapping reading frames from cytoplasmic RNA viruses have their downstream reading frame in +1 orientation relative to the upstream frame. We propose that the evolutionary conservation of the downstream reading frame in +1 orientation in these bicistronic mRNAs is important for its efficient translation.

Original languageEnglish
Pages (from-to)1223-1231
Number of pages9
JournalBiochemistry
Volume35
Issue number4
DOIs
Publication statusPublished - Jan 30 1996

All Science Journal Classification (ASJC) codes

  • Biochemistry

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