Date of Award

1976

Embargo Period

8-1-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biochemistry

College

College of Graduate Studies

First Advisor

Jim Karam

Abstract

The functions of T4 genes 45, 44, and 62 are required for phage DNA replication. Some evidence suggests that in T4-infected E. coli these genes are cotranscribed in the 45 to 44 to 62 direction. In this study regulation of expression of genes 45, 44, and 62 has been examined by using SDS-polyacrylamide gel electrophoretic assays to analyze the protein products synthesized in T4-infected E. coli at various times after infection under different conditions. Genes 45, 44, and 62 were shown to be cotranscribed by the criterion of translational polarity, but the degree of polarity shown by gene 44 nonsense mutations on gene 62 expression was much greater than that shown by a gene 45 nonsense mutation on expression of genes 44 and 62. This difference suggests that genes 45, 44, and 62 may be transcribed in two modes: one mode being initiated at the promotor for gene 45 and a second mode being initiated at a gene 44 promotor. Additionally, characterization of a phage mutation that results in hyperproduction of the 44- and 62-proteins without affecting the level of synthesis of the gene 45 protein supported this hypothesis. The mutation (named H6) mapped between markers in genes 45 and 44, was cis-dominant, did not affect stability of mRNA for gene 44, and did not affect the temporal order of T4 gene expression except that it appeared to cause continued expression of genes 44 and 62 throughout the phage growth cycle. H6 might represent (1) mutation of a naturally occurring promotor to increased efficiency or (2) mutational creation of a secondary promotor for genes 44 and 62.

Rights

All rights reserved. Copyright is held by the author.

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