A hydrophobic region within the adenovirus E1B 19 kDa protein is necessary for the transient inhibition of NF-kappaB activated by different stimuli.
The early transcribed adenovirus proteins E1A and E1B display a variety of functions in the transformation of primary rodent cells and the regulation of apoptosis and transcription. We have recently shown recently that the E1B 19 kDa protein from Adenovirus 5 (Ad 5) can functionally antagonize the stimulatory effect of E1A 13S on the human transcription factor NF-kappaB. Here we show that expression of E1B 19 kDa negatively interfered with the activation of NF-kappaB by different stimuli, such as the E1A 13S protein, and treatment with phorbol ester and tumor necrosis factor alpha. This suggests that E1B 19 kDa acts on a common upstream signaling event. Band shift experiments showed that expression of E1B 19 kDa impaired the generation of the nuclear, DNA-binding form of NF-kappaB. Domain mapping experiments employing various E1B 19 kDa mutants revealed the necessity of a hydrophobic Bcl-2 homology region between amino acids 90 and 96 for NF-kappaB inhibition. Co-transfection experiments showed that the inhibitory effect of E1B 19 kDa on E1A 13S-activated NF-kappaB transcription was gradually lost in the course of time. Thus the continuous stimulatory action of E1A 13S can finally override the antagonistic effects of E1B 19 kDa on NF-kappaB activity. In contrast to E1B 19 kDa, expression of the E1B 55 kDa protein did not result in a de novo activation of NF-kappaB, but co-stimulated the transcriptional potential of activated NF-kappaB.
Limbourg
F P
FP
Institute of Biochemistry and Molecular Biology, Albert-Ludwigs-University, Hermann-Herder-Strasse, D-79104 Freiburg, Germany.
Städtler
H
H
Chinnadurai
G
G
Baeuerle
P A
PA
Schmitz
M L
ML
D017501:Adenovirus E1B Proteins / Q000235:genetics*; D000260:Adenoviruses, Human / Q000235:genetics*; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016328:NF-kappa B / Q000502:physiology*; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D012995:Solubility; D013329:Structure-Activity Relationship; D051841:Transcription Factor RelB; D014157:Transcription Factors; D014158:Transcription, Genetic
D017501:Adenovirus E1B Proteins; D004268:DNA-Binding Proteins; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D011518:Proto-Oncogene Proteins; C497593:RELB protein, human; D012333:RNA, Messenger; D014157:Transcription Factors; D051841:Transcription Factor RelB