TY - JOUR
T1 - Piscirickettsia salmonis cryptic plasmids
T2 - Source of mobile DNA and virulence factors
AU - Ortiz-Severín, Javiera
AU - Travisany, Dante
AU - Maass, Alejandro
AU - Chávez, Francisco P.
AU - Cambiazo, Verónica
N1 - Publisher Copyright:
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2019/12
Y1 - 2019/12
N2 - Four large cryptic plasmids were identified in the salmon pathogen Piscirickettsia salmonis reference strain LF-89. These plasmids appeared highly novel, with less than 7% nucleotidic identity to the nr plasmid database. Plasmid copy number analysis revealed that they are harbored in chromosome equivalent ratios. In addition to plasmid-related genes (plasmidial autonomous replication, partitioning, maintenance, and mobilization genes), mobile genetic elements such as transposases, integrases, and prophage sequences were also identified in P. salmonis plasmids. However, bacterial lysis was not observed upon the induction of prophages. A total of twelve putative virulence factors (VFs) were identified, in addition to two global transcriptional regulators, the widely conserved CsrA protein and the regulator Crp/Fnr. Eleven of the putative VFs were overexpressed during infection in two salmon-derived cellular infection models, supporting their role as VFs. The ubiquity of these plasmids was also confirmed by sequence similarity in the genomes of other P. salmonis strains. The ontology of P. salmonis plasmids suggests a role in bacterial fitness and adaptation to the environment as they encode proteins related to mobilization, nutrient transport and utilization, and bacterial virulence. Further functional characterization of P. salmonis plasmids may improve our knowledge regarding virulence and mobile elements in this intracellular pathogen.
AB - Four large cryptic plasmids were identified in the salmon pathogen Piscirickettsia salmonis reference strain LF-89. These plasmids appeared highly novel, with less than 7% nucleotidic identity to the nr plasmid database. Plasmid copy number analysis revealed that they are harbored in chromosome equivalent ratios. In addition to plasmid-related genes (plasmidial autonomous replication, partitioning, maintenance, and mobilization genes), mobile genetic elements such as transposases, integrases, and prophage sequences were also identified in P. salmonis plasmids. However, bacterial lysis was not observed upon the induction of prophages. A total of twelve putative virulence factors (VFs) were identified, in addition to two global transcriptional regulators, the widely conserved CsrA protein and the regulator Crp/Fnr. Eleven of the putative VFs were overexpressed during infection in two salmon-derived cellular infection models, supporting their role as VFs. The ubiquity of these plasmids was also confirmed by sequence similarity in the genomes of other P. salmonis strains. The ontology of P. salmonis plasmids suggests a role in bacterial fitness and adaptation to the environment as they encode proteins related to mobilization, nutrient transport and utilization, and bacterial virulence. Further functional characterization of P. salmonis plasmids may improve our knowledge regarding virulence and mobile elements in this intracellular pathogen.
KW - Fish pathogen
KW - Gene annotation
KW - MGE
KW - Piscirickettsia salmonis
KW - Plasmids
KW - Prophages
KW - Virulence factors
UR - http://www.scopus.com/inward/record.url?scp=85076309989&partnerID=8YFLogxK
U2 - 10.3390/pathogens8040269
DO - 10.3390/pathogens8040269
M3 - Article
AN - SCOPUS:85076309989
SN - 2076-0817
VL - 8
JO - Pathogens
JF - Pathogens
IS - 4
M1 - 269
ER -