Comparative analyses of a putative Francisella conjugative element.

Area of Science:

• Microbiology
• Genetics
• Plasmid Biology

Background:

• Francisella species are known human and animal pathogens.
• Plasmids play crucial roles in bacterial adaptation and evolution.
• Limited knowledge exists regarding plasmids in Francisella novicida-like strains.

Purpose of the Study:

• To fully sequence and characterize a novel plasmid, pFNPA10, from Francisella novicida-like strain PA10-7858.
• To determine the genetic content and potential functions of pFNPA10.
• To assess the phylogenetic relationship and novelty of pFNPA10 within the Francisella genus.

Main Methods:

• Complete genomic sequencing of the pFNPA10 plasmid.
• Bioinformatic analysis to identify Open Reading Frames (ORFs).
• Homology searches against known plasmid databases.
• Phylogenetic analysis of identified genes and the plasmid as a whole.

Main Results:

• A 41,013-bp circular plasmid, pFNPA10, was identified and sequenced.
• pFNPA10 is significantly larger (8-10 times) than previously characterized Francisella plasmids and shows no homology.
• 57 ORFs were identified, including 9 encoding putative conjugal transfer proteins and a replication protein suggesting theta replication.
• Phylogenetic analysis suggests an origin within an environmental Francisella lineage, indicating pFNPA10 is a novel genetic element.

Conclusions:

• pFNPA10 represents a novel, large, extra-chromosomal genetic element in the Francisella genus.
• Its unique genetic makeup, including potential conjugation genes, warrants further investigation.
• The potential of pFNPA10 as a conjugation vector for Francisella species requires future exploration.