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Toxin genes on pathogenicity islands: impact for microbial evolution
U Dobrindt1, B Janke, K Piechaczek
1Institut für Molekulare Infektionsbiologie, Würzburg, Germany.
Abstract:
Toxin-specific genes are often located on mobile genetic elements such as phages, plasmids and pathogenicity islands (PAIs). The uropathogenic E. coli strain 536 carries two alpha-hemolysin gene clusters, which are part of the pathogenicity islands I536 and II536, respectively. Using different genetic techniques, two additional PAIs were identified in the genome of the E. coli strain 536, and it is likely that further PAIs are located on the genome of this strain. Pathogenicity islands are often associated with tRNA genes. In the case of the E. coli strain 536, the PAI-associated tRNA gene leuX, which encodes a minor leucyl-tRNA, affects the expression of various virulence traits including alpha-hemolysin production. The exact mode of action of the tRNA5Leu-dependent gene expression has to be identified in the future.
Insights
Pathogenicity islands (PAIs) in uropathogenic E. coli strain 536 carry toxin genes. A specific tRNA gene, leuX, influences virulence traits like alpha-hemolysin production, with its exact mechanism requiring further study.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Toxin-specific genes are frequently found on mobile genetic elements like phages, plasmids, and pathogenicity islands (PAIs).
- Uropathogenic Escherichia coli (E. coli) strain 536 possesses two alpha-hemolysin gene clusters, integrated within pathogenicity islands I536 and II536.
- Pathogenicity islands are often linked to tRNA genes, which can play a role in virulence gene expression.
Purpose of the Study:
- To investigate the genetic organization of pathogenicity islands in E. coli strain 536.
- To identify the role of tRNA genes associated with PAIs in the regulation of virulence factors.
Main Methods:
- Genetic analysis techniques were employed to identify and characterize pathogenicity islands.
- Investigated the association between PAI-associated tRNA genes and the expression of virulence traits.
Main Results:
- Two additional pathogenicity islands were identified in E. coli strain 536, suggesting potential for more.
- The PAI-associated tRNA gene leuX was found to influence the expression of multiple virulence traits, including alpha-hemolysin production.
Conclusions:
- E. coli strain 536 harbors multiple pathogenicity islands, contributing to its virulence.
- The tRNA gene leuX plays a regulatory role in virulence gene expression, specifically impacting alpha-hemolysin production.
- Further research is needed to elucidate the precise mechanism of tRNA5Leu-dependent gene expression in virulence.