The subject of this study was a search for the biochemical basis of hypersensitivity to thiols in a mutant of Escherichia coli (IS16). A 1.3 kb chromosomal fragment from E. coli (introduced into the mutant on a plasmid) successfully abolished the hypersensitivity. This fragment contained only one intact gene, ubiX, which codes for polyprenyl-4-hydroxybenzoatelyase. The decarboxylation of octaprenyl-4- hydroxybenzoate in E. coli is catalyzed not only by the ubiX protein but also by the product of ubiD. The ubiquinone content of IS16 was only 2% of that of its parent strain, while the complementing plasmid increased it to 200%. The ubiX genes were amplified from the parent (THU) and from the thiol sensitive mutant (IS16) by PCR and they were sequenced. They had identical sequences which were considerably different from the published sequence. It is therefore assumed that the parent strain was a ubiX genotype, while the thiol sensitive mutant was a ubiXubiD genotype. Thiol hypersensitivity is postulated to be the consequence of the extremely low ubiquinone content.
George T. Javor
E. Clifford Herrmann
Charles W. Slattery
Master of Science (MS)
Year Degree Awarded
Date (Title Page)
Library of Congress/MESH Subject Headings
Sulfhydryl Compounds -- pharmacology; Drug Hypersensitivity; Escherichia coli -- physiology.
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Zeng, Hongying, "A Search for the Cause of Excess Thiol Sensitivity in a Mutant of ESCHERICHIA COLI" (1997). Loma Linda University Electronic Theses, Dissertations & Projects. 1902.
Loma Linda University Electronic Theses and Dissertations
Loma Linda University. Del E. Webb Memorial Library. University Archives