Claudia Trappetti

Claudia Trappetti

School of Biological Sciences

Faculty of Sciences

Eligible to supervise Masters and PhD - email supervisor to discuss availability.


Exploring a new link between sugar metabolism and cell-to-cell signalling.

  • Title: Exploring a new link between sugar metabolism and cell-to-cell signalling.
  • Funding scheme: 51715001: ARC - Discovery Projects
  • Description: LuxS/AI-2 cell-cell signalling has been proposed to be a global language system in bacteria however outside of the Vibrio spp. and some enterobacteria species the detailed evidence for this remains extremely poor. This is exemplified by the current failure to identify in most species any of the receptors, uptake mechanisms or molecular events which might link AI- 2 to the often vague and metabolically determined phenotypes of luxS mutant strains. This project is based on clear preliminary data that demonstrate a signalling event linked to AI-2 in the Gram-positive bacterium Streptococcus pneumoniae. Key aspect of this finding is that the signalling event of the carbohydrate signalling molecule AI-2 is masked by growth in glucose, an invariant component of culture media for Gram-positive bacteria. The main aim of the proposal is to identify the molecular mechanisms of LuxS/AI-2 cell-cell signalling in bacteria. To achieve this aim we will use the model specie Streptococcus pneumoniae for which detailed evidence is available for carbohydrate uptake and related regulatory systems. The objectives of the proposal are: - characterization of the receptor for AI-2 signalling molecule- Identification of the signalling events following AI-2 detection and -validation of the data across other bacteria to provide a more global impact to the research. These objectives will provide detailed molecular mechanisms and provide an understanding of the global nature of LuxS/AI-2 cell-cell signalling mechanisms. While this work aims mainly to resolve the scientific basis of the phenomenon it is our intention to explore the physiological relevance of the AI-2 signalling to identify bottlenecks which could serve as potential antimicrobial targets.
  • Funder name: Australian Research Council
  • Funder reference: DP190102980
  • Investigators: Trappetti C; Paton J; Oggioni M

A tale of two quorum sensing systems that regulate pneumococcal virulence

  • Title: A tale of two quorum sensing systems that regulate pneumococcal virulence
  • Funding scheme: FND000164: University of Adelaide - Research Fellowships Scheme
  • Description: Streptococcus pneumoniae is a Gram-positive bacterium, part of the “normal” nasopharyngeal microflora. However, it can spread to other sites of the body and cause a wide range of illnesses. Despite decades of experimental research on the pneumococcus, the early events whereby this bacterium progresses from harmless colonisation of the human upper respiratory tract to lethal infections, remain a mystery. Communication between bacterial cells is critical for this progression, and is achieved through detection of chemical signalling molecules in a mechanism known as “quorum sensing” (QS). I have been characterising two QS systems used by S. pneumoniae: the Competence Stimulating Peptide (Csp) and, the LuxS/Autoinducer-2 signalling systems. Central to this research has been my discovery that both of these systems influence biofilm formation and most importantly, exogenous synthetic Csp and AI-2 molecules accelerate the progression of disease in S. pneumoniae-infected mice. Based on my previous studies and preliminary data, I hypothesise that these two systems form a complex QS regulatory network, which collectively enables the bacteria to regulate important virulence genes in response to various combinations of environmental, cell density and metabolic stimuli, and that the Csp and AI-2 molecules are central to this network. I will test this hypothesis by addressing the following specific Aims: Aim 1. Investigate the kinetics and population density/signalling molecule thresholds that trigger the two QS systems in S. pneumoniae. Aim 2. Determine the relationship between the two QS systems. Collectively, these studies will provide critical new information on the role of the Csp/AI-2 QS systems in pathogenesis of pneumococcal disease identifying new therapeutic targets to combat this deadly pathogen.
  • Funder name: The University of Adelaide
  • Investigators: Trappetti C

Biofilm and quorum sensing in pneumococcal biology

  • Title: Biofilm and quorum sensing in pneumococcal biology
  • Funding scheme: 51715009: ARC - Discovery Early Career Researcher Award
  • Funder name: Australian Research Council
  • Funder reference: DE140100963
  • Investigators: Trappetti C 

The molecular determinants of biofilm formation in Streptococcus pneumoniae: novel targets for vaccines and therapeutics

  • Title: The molecular determinants of biofilm formation in Streptococcus pneumoniae: novel targets for vaccines and therapeutics
  • Funding scheme: 900834: Garnett Passe & Rodney Williams Memorial Foundation - Research Training Fellowship
  • Funder name: Garnett Passe and Rodney Williams Memorial Foundation
  • Investigators: Trappetti C

 


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