Investigating the production of pneumolysin in Streptococcus pneumoniae.

  • Aimee J Caress

Student thesis: Master's ThesisMaster of Science by Research (MScR)

Abstract

Streptococcus pneumoniae is a clinically significant opportunistic pathogen, made more problematic due to widespread penicillin resistance limiting treatment options. In conjunction with other virulence factors, its single toxin pneumolysin plays a significant role in S. pneumoniae’s pathogenicity, as well as enhancing transmission of the bacteria by increasing inflammation in the upper respiratory tract. In spite of this significance, little is known about how the production of pneumolysin is regulated.
This project aimed to define at what point over a growth curve pneumolysin is produced and secreted by S. pneumoniae. To do this first required the establishment of a growth curve and the characterisation of growth in quantities suitable for protein concentration. Under optimal growth conditions as established in this study, using protein size exclusion spin columns for concentration, pneumolysin was found to be exported from cells at early exponential growth phase in two independent strains of S. pneumoniae D39 and R6.
A putative transcriptional regulator gene spr1738, which has homology to the YebC family and is located downstream of pneumolysin within the transcribed operon, was selected for characterisation by creating a knock-out mutant, R6Δ1738. In both overnight cultures and early growth phase cultures no observable change in the quantity of pneumolysin produced and secreted was observed. Although transcriptional analysis is needed to fully confirm this, this work suggests that this transcriptional regulatory gene does not affect Pneumolysin production and other explanations for an increase in haemolytic activity need to be explored.
Overall, this work contributes to the understanding of the transcription and export requisites of pneumolysin by S. pneumoniae.
Date of Award18 Jun 2024
Original languageEnglish
Awarding Institution
  • University of Bristol
SupervisorJim Spencer (Supervisor) & Ruth C Massey (Supervisor)

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