Hypoxanthine Excision from DNA in Escherichia Coli and Saccharomyces Cerevisiae
Loading...
Authors
Gary, Sonja L.
Issue Date
1992
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Defective temporal regulation of some DNA repair enzymes,
including hypoxanthine-DNA glycosylase is in part responsible for Bloom's
syndrome. Identification of this enzyme in yeast would provide a simple
eukaryotic system in which to study its function and regulation. An attempt
was made to identify hypoxanthine-DNA glycosylase activity in
Saccharomyces cerevisiae. Wild type (wt) and uracil-DNA glycosylase
deficient (ung-) strains of both E. coli and S. cerevisiae were transformed with
double-stranded phagemids pRS316 and pRS314 prepared from single-stranded
normal (obtained from a wild type strain) and uracil-containing
DNA (U-DNA). The second strand of each was synthesized to contain
various ratios of inosine:guanine and the second strand of U-DNA was also
synthesized with different ratios of uracil:thymine and transformed into both
strains of each species as a control. Wild typeE. coli exhibited a pattern of
more transform ants at lower I:G ratios even when background numbers of
transformants, from incomplete degradation of the uracil strand, were taken
into account. This suggests that hypoxanthine-DNA glycosylase is inefficient
at cleaving I -C base pairs. The sustained ability of inosine-uracil hybrids to
transform both wt and ung- S. cerevisiae strains at wild type levels, after
degradation of the uracil strand suggests that hypoxanthine-DNA glycosylase
in yeast is inefficient at cleaving I-C base pairs, if it is present at all.
Description
v, 26 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.