Open AccessSpontaneous Excision of the Salmonella enterica Serovar Enteritidis-Specific Defective Prophage-Like Element φSE14
Author(s) -
Carlos A. Santiviago,
Carlos J. Blondel,
Carolina Paz Quezada,
Cecilia A. Silva-Valenzuela,
Pía Tobar,
Steffen Porwollik,
Michael McClelland,
Helene AndrewsPolymenis,
Carlos A. Toro,
Mercedes Zaldı́var,
Inés Contreras
Publication year - 2010
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.00270-09
Subject(s) - prophage , biology , salmonella enteritidis , salmonella enterica , serotype , microbiology and biotechnology , salmonella , virology , plasmid , bacteria , genetics , escherichia coli , gene , bacteriophage
Salmonella enterica serovar Enteritidis has emerged as a major health problem worldwide in the last few decades. DNA loci unique toS . Enteritidis can provide markers for detection of this pathogen and may reveal pathogenic mechanisms restricted to this serovar. Anin silico comparison of 16Salmonella genomic sequences revealed the presence of an ∼12.5-kb genomic island (GEI) specific to the sequencedS . Enteritidis strain NCTC13349. The GEI is inserted at the 5′ end of geneydaO (SEN1377 ), is flanked by 308-bp imperfect direct repeats (attL andattR ), and includes 21 open reading frames (SEN1378 toSEN1398 ), encoding primarily phage-related proteins. Accordingly, this GEI has been annotated as the defective prophage SE14 in the genome of strain NCTC13349. The genetic structure and location of φSE14 are conserved in 99 of 103 wild-type strains ofS . Enteritidis studied here, including reference strains NCTC13349 and LK5. Notably, an extrachromosomal circular form of φSE14 was detected in every strain carrying this island. The presence ofattP sites in the circular forms detected in NCTC13349 and LK5 was confirmed. In addition, we observed spontaneous loss of atetRA -tagged version of φSE14, leaving an emptyattB site in the genome of strain NCTC13349. Collectively, these results demonstrate that φSE14 is an unstable genetic element that undergoes spontaneous excision under standard growth conditions. An internal fragment of φSE14 designated Sdf I has been used as a serovar-specific genetic marker in PCR-based detection systems and as a tool to determineS . Enteritidis levels in experimental infections. The instability of this region may require a reassessment of its suitability for such applications.