KipOTIA detoxifies 5-oxoproline and promotes growth of Clostridioides difficile Pubblico

Lee, Cheyenne (Summer 2024)

Permanent URL: https://etd.library.emory.edu/concern/etds/pz50gx81b?locale=it
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Abstract

Clostridioides difficile is a Gram-positive anaerobic pathogen that is the primary cause of antibiotic associated diarrhea. Symptoms of infection range from severe abdominal pain and diarrhea to life-threatening pseudomembranous colitis. There are approximately 55 cases per 100,000 persons with a recurrence rate of 20 – 35%, making C. difficile infection a heavy healthcare burden. To be efficiently transmitted and cause infection, C. difficile must form a resistant endospore. Endospore formation is tightly regulated since forming a spore is energetically costly and an irreversible commitment. In Bacillus subtilis, the Kinase Inhibitory Protein, KipI, binds to the primary sporulation initiating kinase to repress sporulation. KipA antagonizes KipI to prevent KipI from repressing sporulation. Additionally, the KipI and KipA proteins function as part of a complex with KipO to detoxify the metabolic by-product 5-oxoproline. This thesis sought to characterize the C. difficile KipOTIA orthologs to determine their impacts on sporulation and 5-oxoproline metabolism. We deleted kipIA and kipOTIA and discovered that they have no significant impacts on sporulation. We also demonstrate that the kip operon encodes a 5-oxoprolinase capable of detoxifying 5-oxoproline. In addition to detoxification, we show that the C. difficile 5-oxoprolinase allows 5-oxoproline to be used as a nutrient source to promote growth.

Table of Contents

Chapter 1: Introduction…………………………………………………………………………......................................................................................................................................................1

 

Chapter 2: KipOTIA detoxifies 5-oxoproline and promotes the growth of Clostridioides difficile................................................................................................................................ 23

 

Chapter 3: Genetic mechanisms governing sporulation initiation in Clostridioides difficile……………………………………………………………………………………………...............................62

 

Chapter 4: Discussion………………………………………………………………………….……….............................................................................................................................................84

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