Elucidation of the roles of newly identified Pseudomonas aeruginosa transcriptional regulators required for chronic infection

  • Robert Wilson

Student thesis: Master's Thesis

Abstract

The opportunistic pathogen Pseudomonas aeruginosa is the most frequently isolated bacteria from the cystic fibrosis lung. It is responsible for a multitude of nosocomial infections and many strains exhibit multidrug resistance which presents a serious challenge to healthcare providers. P. aeruginosa is capable of adapting to its hosts in order to survive the immune response and treatment with antibiotics. An important aspect of this process is the production of an alginate-based biofilm which is caused by constitutive activation of the alginate operon regulator mucA which regulates capsule formation. Sequencing data has shown that one pair of clinical isolates, C1426 & C1433, contain a unique 5kbp extension to the Pseudomonas Pathogenicity Island-1 (PAPI1). This extension contains sequences which are homologous to a variety of genes including σ and anti-σ factors which could regulate pathogenic mechanisms in these strains. Knockout mutants of these newly discovered genes are being developed to determine their regulatory targets. It has also been found that the late clinical isolate J1532 produces less alginate than late isolate C1433. Examination of the sequence of anti- σ factor algU has found possible second site suppressor mutations in J1532 which could account for the reduction in the rate of biofilm formation. LacZ fusion strains are being used to determine if there is a similar difference in promoter activity. Other elements of the alginate operon are believed to be regulated by the alternative σ factor σ54. σ54 is activated by regulatory proteins with GAFTGA motifs. In this study, GAFTGA protein fragments will be over-expressed in the clinical isolates to determine if alginate production is regulated by σ54. It is hoped that this research will improve understanding of biofilm production in pathogenic, host-adapted strains of P. aeruginosa for the purpose of developing therapies to treat drug resistant infections.
Date of Award13 Jan 2015
Original languageEnglish
Awarding Institution
  • University Of Strathclyde

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