Adenovirus E1B 19-kilodalton protein overcomes the cytotoxicity of E1A proteins

White, E., Cipriani, R., Sabbatini, P., Denton, A. (June 1991) Adenovirus E1B 19-kilodalton protein overcomes the cytotoxicity of E1A proteins. J Virol, 65 (6). pp. 2968-78. ISSN 0022-538X (Print)0022-538X (Linking)

URL: http://www.ncbi.nlm.nih.gov/pubmed/1851867

Abstract

Infection with adenovirus mutants carrying either point mutations or deletions in the coding region for the 19-kDa E1B gene product (19K protein) causes degradation of host cell and viral DNAs (deg phenotype) and enhanced cytopathic effect (cyt phenotype). Therefore, one function of the E1B 19K protein is to protect nuclear DNA integrity and preserve cytoplasmic architecture during productive adenovirus infection. When placed in the background of a virus incapable of expressing a functional E1A gene product, however, E1B 19K gene mutations do not result in the appearance of the cyt and deg phenotypes. This demonstrated that expression of the E1A proteins was responsible for inducing the appearance of the cyt and deg phenotypes. By constructing a panel of viruses possessing E1A mutations spanning each of the three E1A conserved regions in conjunction with E1B 19K gene mutations, we mapped the induction of the cyt and deg phenotypes to the amino-terminal region of E1A. Viruses that fail to express conserved region 3 (amino acids 140 to 185) and/or 2, (amino acids 121 to 185) or nonconserved sequences between conserved regions 2 and 1 of E1A (amino acids 86 to 120) were still capable of inducing cyt and deg. This indicated that activities associated with these regions, such as transactivation and binding to the product of the retinoblastoma susceptibility gene, were dispensable for induction of E1A-dependent cytotoxic effects. In contrast, deletion of sequences in the amino terminus of E1A (amino acids 22 to 107) resulted in extragenic suppression of the cyt and deg phenotypes. Therefore, a function affected by deletion of amino acids 22 to 86 of E1A is responsible for exerting cytotoxic effects in virally infected cells. Furthermore, transient high-level expression of the E1A region using a cytomegalovirus promoter plasmid expression vector was sufficient to induce the cyt and deg phenotypes, demonstrating that E1A expression alone is sufficient to exert these cytotoxic effects and that other viral gene products are not involved. Finally, placing E1A expression under the control of a strong promoter did not alter the requirement for E1B in the transformation of primary cells. One possibility is that the E1B 19K protein is required to overcome the cytotoxic effects of E1A protein expression and thereby enable primary cells to become transformed.

Item Type: Paper
Uncontrolled Keywords: Adenoviridae Infections/genetics/pathology Adenovirus Early Proteins Adenoviruses, Human/*genetics/growth & development Cytomegalovirus/genetics Cytopathogenic Effect, Viral/genetics DNA, Viral/metabolism Gene Expression HeLa Cells/microbiology Molecular Weight Mutation Nucleic Acid Denaturation Oncogene Proteins, Viral/*genetics Plasmids Promoter Regions, Genetic Transformation, Genetic
Subjects: organism description > virus > adenovirus
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > DNA, RNA structure, function, modification > genes, structure and function > gene expression
CSHL Authors:
Communities: CSHL labs > Stillman lab
Depositing User: Matt Covey
Date: June 1991
Date Deposited: 14 Jan 2016 18:09
Last Modified: 14 Jan 2016 18:09
PMCID: PMC240940
Related URLs:
URI: http://repository.cshl.edu/id/eprint/32033

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