Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Due to the complexity of the T4 uvsX-uvsY DNA repair pathway, we have attempted to define the functions and repair mechanisms involved in the pathway, using several different techniques. The DNA repair-recombination functions of the pathway were analyzed biochemically and genetically to aid in understanding the role of these functions in the cell.;To study the functions of the uvsX and uvsY gene products, DNA intermediates formed after uv-irradiation were extracted from uvsX and uvsY mutant-infected cells and analyzed by sucrose gradient centrifugation. Results of this analysis suggested that the uvsX and uvsY gene products function in a DNA "joining" reaction.;The uvsX and uvsY genes are also involved in DNA maturation since DNA maturation-defective mutations in gene 49 are suppressed by uvsX and uvsY mutations. We have studied the role of the DNA repair-recombination functions in DNA maturation by analyzing the suppressors of a gene 49 mutation. Mutations in genes 46, 47, 59, uvsX and uvsY suppress gene 49 mutations. This suggests that the DNA repair-recombination genes function in a DNA processing pathway and that the suppression of gene 49 mutations occurs because the DNA intermediates formed by these DNA repair-defective mutants bypass the requirement for the gene 49 function.;We have analyzed the interrelationships of the repair-recombination functions by studying extragenic suppressors of mutations in these genes. A study of these suppressors can indicate interactions between the various gene products involved. Using this approach, we have isolated two new suppressors, sur and uvsU. The sur mutation is a general suppressor of mutations in the DNA repair-recombination genes. In contrast, the uv-sensitive mutation uvsU, specifically suppresses uvsX mutations. Further studies of uvsU have led us to propose a model whereby the DNA repair-recombination functions are coupled to DNA replication.



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