Promoter inactivation or inhibition by sequence-specific methylation and mechanisms of reactivation.
In studies on adenovirus promoters, predominantly on the late E2A promoter of adenovirus type 2 (Ad2), we have demonstrated by a number of experimental approaches that the sequence-specific methylation of three 5'-CCGG-3' sequences inactivates this promoter. Recently, we have developed a cell-free transcription system in which the methylation-inactivation of eukaryotic promoters can be studied in detail. It has also been shown that methylation-caused promoter inactivation can be reversed by the 289 amino acid E1A protein of Ad2 or of adenovirus type 5. In the presence of this protein with a transactivating effect, transcription is initiated at the authentic cap site of the methylated late E2A promoter. A similar reactivation of the methylated late E2A promoter can also be effected by a cis-acting genetic element, i.e., the strong enhancer of human cytomegalovirus. Further studies will be directed toward the biochemical mechanisms of promoter silencing by sequence-specific methylations.
Doerfler
W
W
Institute of Genetics, University of Cologne, Germany.
Hoeveler
A
A
Weisshaar
B
B
Dobrzanski
P
P
Knebel
D
D
Langner
K D
KD
Achten
S
S
Müller
U
U
D000260:Adenoviruses, Human / Q000235:genetics*; D001483:Base Sequence; D003587:Cytomegalovirus / Q000235:genetics; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D005814:Genes, Viral; D006801:Humans; D008745:Methylation; D011401:Promoter Regions, Genetic; D014158:Transcription, Genetic
D004279:DNA, Viral