Open AccessEpigenetic Control of Salmonella enterica O-Antigen Chain Length: A Tradeoff between Virulence and Bacteriophage Resistance
Author(s) -
Ignacio Cota,
María Antonia Sánchez-Romero,
Sara B. Hernández,
M. Graciela Pucciarelli,
Francisco Garcı́a-del Portillo,
Josep Casadesús
Publication year - 2015
Publication title -
plos genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.587
H-Index - 233
eISSN - 1553-7404
pISSN - 1553-7390
DOI - 10.1371/journal.pgen.1005667
Subject(s) - biology , phase variation , salmonella enterica , salmonella , myoviridae , bacteriophage , virulence , microbiology and biotechnology , operon , antigenic variation , virology , genetics , antigen , gene , bacteria , escherichia coli
The Salmonella enterica opvAB operon is a horizontally-acquired locus that undergoes phase variation under Dam methylation control. The OpvA and OpvB proteins form intertwining ribbons in the inner membrane. Synthesis of OpvA and OpvB alters lipopolysaccharide O-antigen chain length and confers resistance to bacteriophages 9NA (Siphoviridae), Det7 (Myoviridae), and P22 (Podoviridae). These phages use the O-antigen as receptor. Because opvAB undergoes phase variation, S . enterica cultures contain subpopulations of opvAB OFF and opvAB ON cells. In the presence of a bacteriophage that uses the O-antigen as receptor, the opvAB OFF subpopulation is killed and the opvAB ON subpopulation is selected. Acquisition of phage resistance by phase variation of O-antigen chain length requires a payoff: opvAB expression reduces Salmonella virulence. However, phase variation permits resuscitation of the opvAB OFF subpopulation as soon as phage challenge ceases. Phenotypic heterogeneity generated by opvAB phase variation thus preadapts Salmonella to survive phage challenge with a fitness cost that is transient only.