Genomic sequencing reveals absence of DNA methylation in the major late promoter of adenovirus type 2 DNA in the virion and in productively infected cells.
By using methylation-sensitive restriction endonucleases, we have previously provided evidence that adenovirus type 2 (Ad2) virion DNA or free intranuclear Ad2 DNA in productively infected hamster or human cells is not methylated. We have now chosen a different experimental approach and have investigated the major late promoter (MLP) sequence of Ad2 DNA for the presence of 5-methyldeoxycytidine (5-mC) residues with the genomic sequencing technique. This study has been prompted by the finding that the MLP of Ad2 DNA can be inactivated by sequence-specific methylation in experiments in which a MLP-chloramphenicol acetyltransferase construct has been transcribed in a cell-free system from HeLa cell nuclear extracts. Virion Ad2 DNA and Ad2 DNA isolated from productively infected human or hamster cells between 1 and 48 h post-infection (p.i.) have now been analyzed. There is no evidence for the presence of 5-mC in the cytidine positions in the MLP of any of these Ad2 preparations. We conclude that DNA methylation does not seem to play a role in the early-late control of this viral promoter. The sensitivity of the genomic sequencing technique does not permit us to exclude the unlikely presence of 5-mC in a few Ad2 DNA molecules.
Kämmer
C
C
Institut für Genetik, Universität zu Köln, Germany.
Doerfler
W
W
D000260:Adenoviruses, Human / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D006224:Cricetinae; D004279:DNA, Viral / Q000737:chemistry* / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000032:analysis; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D008745:Methylation; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017422:Sequence Analysis, DNA / Q000379:methods*; D014771:Virion / Q000737:chemistry*
D004279:DNA, Viral; D003841:Deoxycytidine; C016569:5-methyldeoxycytidine