cis-Acting packaging motifs of porcine adenovirus type 3.
The cis-acting packaging domain is required for selective encapsidation of adenovirus DNA into preformed empty capsids late in the viral life cycle. Earlier, it was demonstrated that the cis-acting packaging domain of porcine adenovirus type (PAdV)-3 is located between nucleotide position (nt) 212 and 531 at the left end genome which contains six AT/GC rich motifs. Removal of packaging domain from left end to the right end of the genome produced a viable mutant virus suggesting that the identified cis-acting packaging domain represents the DNA sequences required for selective packaging of PAdV-3 DNA, whose position and orientation appear to be flexible. Here, by constructing and analyzing a panel of virus mutants carrying deletions or linker scanning mutations in AT/GC rich sequences, we examined the significance of the continuous A/T or G/C sequences individually in the viral packaging process. In contrast to consensus bipartite structure (5'-TTTGN8CG-3') described for most of packaging motifs of human adenovirus type 5 (HAdV-5), the packaging motifs I, II, III, and IV of PAdV-3 displayed a tripartite structure in which the continuous A/T nucleotides were flanked by G/C-rich sequences. Mutations in both continuous A/T nucleotides and its flanking GC-rich sequences reduced the packaging efficiency of mutants to varying degrees. In addition, although the continuous A/T sequences were present in all of the packaging motifs, their significance in the packaging process appears to vary within each packaging motif.
Xing
Li
L
Vaccine and Infectious Disease Organization, 120 Veterinary Road, University of Saskatchewan, Saskatoon, Canada S7N 5E3.
Tikoo
Suresh Kumar
SK
D000260:Adenoviruses, Human / Q000235:genetics; D025662:Adenoviruses, Porcine / Q000235:genetics* / Q000502:physiology; D000818:Animals; D004279:DNA, Viral / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral; D019065:Virus Assembly / Q000502:physiology*
D004279:DNA, Viral