Date of Award

Spring 1997

Document Type

Restricted Thesis

Terms of Use

© 1997 Brenda L. Ayers. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Biology

First Advisor

Amy Cheng Vollmer

Abstract

Sulfometuron Methyl (SM) is a sulfonylurea herbicide that prevents branched-chain amino acid biosynthesis in plants and bacteria by inhibiting the action of acetolactate synthase (ALS). The E. coli genome was screened for promoters responsive to SM. TolC⁻ mutants of E. coli were transformed with a plasmid containing the luxCDABE reporter genes downstream of random fragments of the E. coli genome. The presence of SM-responsive promoters among the random fragments was marked by induction of bioluminescence. Plasmid pDEW309 contained a SM- responsive insert that mapped to the locus of poxB, the structural gene for pyruvate oxidase. Several other promoters were identified as SM-responsive including sohA (activation of Lon protease) and ldcH (lysine decarboxylase). Placement of pDEW309 in a tolC⁺ background did not prevent the response of poxB to SM. In addition to a response to SM, poxB also showed a response to glyphosate. salicylate, and methyl viologen (paraquat). poxB is known to be a member of a family of genes regulated by rpoS; however, involvement of poxB in the oxidative stress response has not been shown. Induction experiments show both that poxB is under the control of the oxidative stress regulon, soxRS, and that a tolC⁻ background is not required to observe a response to SM by poxB.

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