Skip to Navigation
Auburn University Homepage
A-Z Index | Map | People Finder
Auburn University Logo
Electronic Theses and Dissertations
Skip to Main Content
Main Navigation 
  • AUETD Home
  • Graduate School
JavaScript is disabled for your browser. Some features of this site may not work without it.
View Item 
  •   AUETD Home
  • View Item
  •   AUETD Home
  • View Item

Characterization of the Glyoxylate Pathway in Pseudomonas aeruginosa

View/Open
Dissertation (514.2Kb)
Date
2009-12-17
Author
Hagins, Jessica
Type of Degree
dissertation
Department
Biological Sciences
Metadata
Show full item record
Abstract
Pseudomonas aeruginosa infections are the leading cause of lung dysfunction and mortality in Cystic Fibrosis (CF) patients. Adaptation of P. aeruginosa to become a chronic pathogen of the CF lung includes acquisition of mutations that facilitate the prolonged survival of the bacterium in that environment. Thus in order to understand the adaptation strategies of the bacterium, it is imperative to study and characterize the actual CF isolates in addition to the non-CF isolates of P. aeruginosa. To identify chronic infection mechanisms of P. aeruginosa CF isolates, the Silo-Suh lab isolated transposon insertion mutants of a typical CF isolate strain, FRD1, that were decreased in virulence in an alfalfa seedling model of infection. One of the mutants contained a transposon insertion in aceA which encodes for isocitrate lyase, one of two enzymes involved in the glyoxylate pathway. The focus of my research was to characterize the expression of aceA and activity of isocitrate lyase to determine whether preferential utilization of the glyoxylate pathway is a part of the adaptation strategy for P. aeruginosa in the CF lung. I determined that the expression of the aceA gene is deregulated in the CF isolate FRD1 compared to the non-CF isolate PAO1. Moreover, deregulation of aceA appears to be common to other CF isolates of P. aeruginosa, suggesting this phenotype is important for adaptation of P. aeruginosa in the lung. In an effort to elucidate the molecular mechanism of aceA deregulation in FRD1, I discovered that RpoN, an alternative sigma factor, negatively regulates aceA expression in PAO1. This is a unique role for this sigma factor. The exact mechanism by which aceA expression is deregulated by RpoN in FRD1 is unclear since this sigma factor appears to be active in FRD1. Thus it is likely that during adaptation, P. aeruginosa acquires a knockout mutation in a RpoN regulated gene whose role is to repress aceA expression in non-CF isolates. Finally, I determined that glcB, encoding for malate synthase, the second key enzyme of the glyoxylate pathway, is also required for virulence of P. aeruginosa on alfalfa and its expression is deregulated in FRD1 compared to PAO1. In addition, expression of a glcB is negatively regulated by RpoN in PAO1. This is the first study to systematically characterize expression of the glyoxylate pathway in P. aeruginosa and my data demonstrate the importance of this pathway for chronic infection isolates.
Files
Name:
Jessica Hagins 2009.pdf  
Size:
514.2Kb
URI
http://hdl.handle.net/10415/2013

Browse

All of AUETDBy Issue DateAuthor / AdvisorTitlesDepartments

My Account

Login

Auburn University Libraries | 231 Mell Street | Auburn, Alabama 36849 | (334) 844-4500 or (800) 446-0387 |

 

Auburn University |Auburn, Alabama 36849 |(334) 844-4000 |

Website Feedback |Privacy |Copyright ©