Title page for ETD etd-11272006-133747


Type of Document Dissertation
Author Varga, John Joseph
Author's Email Address jvarga@vt.edu
URN etd-11272006-133747
Title The Role of CcpA in Regulating the Carbon-Starvation Response of Clostridium perfringens
Degree PhD
Department Biological Sciences
Advisory Committee
Advisor Name Title
Melville, Stephen B. Committee Chair
Boyle, Stephen M. Committee Member
Chen, Jiann-Shin Committee Member
Popham, David L. Committee Member
Keywords
  • sporulation
  • transposon
  • food poisoning
  • CcpA
  • motility
  • type four pili
  • comparative genomics
  • biofilm
  • Clostridium perfringens
Date of Defense 2006-09-01
Availability unrestricted
Abstract
Clostridium perfringens is a significant human pathogen, causing 250,000 cases of food poisoning in addition to several thousand potentially lethal cases of gas gangrene each year in the United States. Historically, work in this field has centered around toxin production, as C. perfringens can produce over 13 toxins. This work expands the knowledge of the starvation-response of C. perfringens, which includes several potential virulence factors, sporulation, motility and biofilm formation. Sporulation protects cells from a variety of stresses, including starvation. Efficient sporulation requires the transcriptional regulator CcpA, mediator of catabolite repression. Sporulation is repressed by glucose, but, surprisingly, in a CcpA-independent fashion. C. perfringens cells in a biofilm are resistant to a number of environmental stresses, including oxygen and antibiotics. Biofilm formation is repressed by glucose, and other carbohydrates, independently of CcpA. Gliding motility, a type four pili (TFP)-dependent phenomenon, affords C. perfringens with a mechanism for moving across a solid surface in response to carbohydrate starvation, while carbohydrates supplementation at high levels delay the initiation of the motility response. CcpA is required for the proper initiation of motility, a ccpA-C. perfringens strain showed a considerable increase in the time to initiation of motility on lactose and galactose, and was unable to move at all in the presence of glucose. Gliding motility represents the most significant finding of this work. TFP were previously undescribed in any Gram-positive bacterial species, and this work produced genetic evidence suggesting their presence in all members of the clostridia, and physical evidence for TFP-dependent gliding motility in a second species, C. beijerinckii.
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