Previous Article | Next Article ![]()
Journal of Virology, September 2007, p. 9623-9632, Vol. 81, No. 18
0022-538X/07/$08.00+0 doi:10.1128/JVI.00771-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Institut für Immunologie, Friedrich-Loeffler-Institut, D-72001 Tübingen, Germany
Received 10 April 2007/ Accepted 20 June 2007
The calicivirus minor capsid protein VP2 is expressed via reinitiation of protein synthesis after termination of translation of the preceding VP1 gene. A sequence element of about 80 nucleotides denoted "termination upstream ribosomal binding site" (TURBS) (25) is crucial for reinitiation. Deletion mapping in the TURBS of a rabbit calicivirus identified two short sequence motifs that were crucial for VP2 expression. Motif 1 is conserved among caliciviruses and is complementary to a sequence in the 18S rRNA. Single-residue exchanges in this motif severely impaired reinitiation when they affected the putative rRNA binding, whereas an exchange preserving complementarity had only a minor effect. Single exchanges in motif 2 were rather well tolerated, but the introduction of double exchanges almost blocked VP2 expression. In contrast, the deletion analyses showed that the RNA between the two motifs is of minor importance. The distance between motif 2 and the start site was found to be important, since deletions of increasing length in this sequence or upstream positioning of the start codon reduced VP2 expression stepwise to low levels, whereas multiple-nucleotide exchanges in this region were tolerated. The low flexibility of the arrangement of TURBS motif 2 and the start codon stand in marked contrast to the requirements with regard to the location of the stop codon of the preceding VP1 gene, which could be moved far downstream with continuous reduction, but without loss, of VP2 translation. The sequence mapping resulted in a refined model of the reinitiation mechanism leading to VP2 expression.
Published ahead of print on 27 June 2007.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»