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Published on: October 8, 2012
pFiD188, the linear virulence plasmid of Rhodococcus fascians D188
Isolde Francis1, Annick De Keyser, Philippe De Backer
1Department of Plant Biotechnology and Bioinformatics, VIB, 9052 Gent, Belgium.
Molecular Plant-Microbe Interactions : MPMI
|April 10, 2012
Summary
The Rhodococcus fascians linear plasmid, pFiD188, shares common origins with other Rhodococcus species. Unique regions contribute to virulence, with some genes potentially acquired through horizontal gene transfer.
Area of Science:
- Microbiology
- Plant Pathology
- Genetics
Background:
- Rhodococcus fascians is a unique phytopathogen with virulence genes located on a linear plasmid.
- Understanding the origin and virulence strategy of this broad-spectrum pathogen requires detailed analysis of its linear plasmid.
Purpose of the Study:
- To determine the complete DNA sequence of the linear plasmid pFiD188 from R. fascians strain D188.
- To investigate the origin of the linear plasmid and the virulence mechanisms of R. fascians.
Main Methods:
- Whole-genome sequencing of the linear plasmid pFiD188 (198,917 bp).
- Comparative analysis of syntenic regions with linear plasmids from related Rhodococcus species.
- Mutational analysis of specific genes (pFi_086, pFi_102) and functional analysis of virulence loci (stk, nrp).
Main Results:
- Identified four syntenic regions shared with other Rhodococcus linear plasmids, suggesting a common evolutionary origin.
- Discovered three unique regions in pFiD188, with specific loci (stk, nrp) showing limited roles in symptom development compared to known virulence factors (fas, att, hyp).
- Conserved region R2, containing cutinase and peptidase homologs, is implicated in plasmid dispersal and suggests a novel role for actinobacterial cutinases in conjugation.
Conclusions:
- pFiD188 represents a typical rhodococcal linear plasmid with a composite structure.
- The plasmid encodes essential functions for maintenance and accessory functions, including virulence and host interaction, with potential horizontal gene transfer contributing to its genetic makeup.
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