tailieunhanh - Báo cáo khoa học: "A case for a CUG-initiated coding sequence overlapping torovirus ORF1a and encoding a novel 30 kDa product"

A case for a CUG-initiated coding sequence overlapping torovirus ORF1a and encoding a novel 30 kDa product | Virology Journal BioMed Central Open Access Short report A case for a CUG-initiated coding sequence overlapping torovirus ORFIa and encoding a novel 30 kDa product Andrew E Firth 1 and John F Atkins 1 2 Address 1BioSciences Institute University College Cork Cork Ireland and 2Department of Human Genetics University of Utah Salt Lake City UT 84112-5330 USA Email Andrew E Firth - John F Atkins - Corresponding authors Published 8 September 2009 Received 9 August 2009 Accepted 8 September 2009 Virologyjournal 2009 6 136 doi 1743-422X-6-136 This article is available from http content 6 1 136 2009 Firth and Atkins licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract The genus Torovirus order Nidovirales includes a number of species that infect livestock. These viruses have a linear positive-sense ssRNA genome of 25-30 kb encoding a large polyprotein that is expressed from the genomic RNA and several additional proteins expressed from a nested set of 3 -coterminal subgenomic RNAs. In this brief report we describe the bioinformatic discovery of a new apparently coding ORF that overlaps the 5 end of the polyprotein coding sequence ORFIa in the 2 reading frame. The new ORF has a strong coding signature and in fact is more conserved at the amino acid level than the overlapping region of ORF1a. We propose that the new ORF utilizes a non-AUG initiation codon - namely a conserved CUG codon in a strong Kozak context - upstream of the ORF1a AUG initiation codon resulting in a novel 258 amino acid protein dubbed 30K . Findings The genus Torovirus belongs to the family Coronaviridae in the order Nidovirales. Species include Bovine torovirus Equine torovirus and Porcine torovirus. As