Year: 2015
Type: dissertation
Abstract: Legionella pneumophila, the major causative agent of the severely pneumonic Legionnaires' disease, is an intracellular bacterial pathogen that is able to exploit aquatic protozoa as well as human alveolar macrophages as hosts for replication.After internalisation, the Legionella containing vacuole (LCV) avoids fusion with the endosomal pathway and intercepts endoplasmic reticulum (ER)-derived early secretory vesicles prior to their transport to the Golgi.This aids in the formation of a vacuole that supports bacterial replication and is driven by effector proteins translocated by the Dot/Icm type IV secretion system.Apart from the Dot/Icm system, few genes have been identified that play a major role in intracellular replication.In this study, we constructed and screened a library of 10,006 L. pneumophila transposon mutants for attenuated intracellular replication within the amoebae Acanthamoeba castellanii.34 mutants were identified, 21 of which carried insertions into the Dot/Icm Type IV secretion system.In addition to these, insertions into seven novel genes were discovered, including lpw27511 and sdeC.lpw27511 encodes a transcriptional regulator of the LuxR family.Its regulatory targets were identified in a DNA microarray, however, the majority of identified targets were weakly affected and there was no obvious explanation for the replication defect observed for the transposon mutant.Further analysis of an in-frame lpw27511 deletion mutant showed that the defined mutant did not show the intracellular replication defect seen for the transposon mutant.Unfortunately subsequent investigations could not find an explanation for the replication defect originally observed for the transposon mutant.sdeC encodes a Dot/Icm translocated effector and we investigated the contribution of this protein to L. pneumophila pathogenesis further.sdeC was required for full replication of L. pneumophila in amoebae, macrophages and in the lungs of A strain mice.HEK293T cells transfected with GFP-tagged SdeC showed that SdeC co-localised I wish to acknowledge the following people for their invaluable assistance with this study.
Author: Adam J. Vogrin
Language: English
Subfield: Endocrinology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2291225357