Characterization of vaccinia virus promoters and identification of their corresponding cellular transcription factors

Xu Liu, Purdue University

Abstract

The Poxviridae is composed of large and complex DNA viruses, of which vaccinia virus is the laboratory prototype. The entire vaccinia virus life cycle occurs in the host cell cytoplasm, and is regulated at the level of transcription. There are three classes of viral genes: early, intermediate and late. The activation of each class of genes depends on prior gene expression and is characterized by a regulatory cascade. To study this unique viral transcriptional regulation, detailed characterizations of promoter structures for the intermediate and late genes were conducted. For both classes, the specific length and sequence requirements of two identified critical regions, termed the core and the initiator elements were defined. In addition, the importance of the spacer region was also demonstrated. The identified upstream core elements in both the intermediate and late promoter were shown to be the recognition sites for the ubiquitous cellular nuclear transcription factor, TATA binding protein. Its involvement in the viral transcription machinery was substantiated by various in vivo and in vitro experiments. A transcription initiation model for each of the intermediate and late classes is proposed based on the eukaryotic RNA polymerase II model. The overall evolutionary significance deduced from the similarities between viral transcription and eukaryotic transcription systems are discussed.

Degree

Ph.D.

Advisors

Broyles, Purdue University.

Subject Area

Biochemistry

COinS