THE CONTROL OF EARLY GENE EXPRESSION IN ADENOVIRUS
Abstract
Adenovirus gene expression can be conveniently divided into two distinct phases during a lytic infection, delineated by the onset of viral DNA replication. Of the six genes expressed in the early phase, four, E1b, E2a, E3, and E4 are controlled by a fifth, E1a. The control of these early genes by E1a has been examined by the construction of plasmids which fuse the putative control regions of the early genes to an assayable gene. The subsequent introduction of the fusion plasmids into tissue culture cells either with or without the introduction of a plasmid which can express E1a has indicated that the ability of the early genes to respond to E1a is encoded in the non-transcribed DNA 5' to the structural gene. In addition these studies have shown that E1a induction of early gene expression is transcriptional, trans acting and independent of additional viral components. The 5' sequences required for responsiveness of the E3 control region to E1a have been shown to reside in sequences between 105 and 80 base pairs away from the transcriptional start site of the E3 gene. This was demonstrated by analysis of the transcriptional activity of E3 control regions carrying deletions which ended at specific points upstream from the transcription initiation site. Finally, this study has identified the existence of a cis acting activator of transcription in the left hand end of the adenovirus genome. This activator is proposed to be an enhancer element, in the same class as those already reported for SV40 and polyoma virus.
Degree
Ph.D.
Subject Area
Biology
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