Genetic Tools for Use with Listeria monocytogenes

The number and sophistication of genetic tools that have become available in recent years for the molecular characterization of Listeria monocytogenes have continued to increase. Plasmid vectors, reporter genes, systems designed for transposon mutagenesis, heterologous expression systems, integration vectors, and transducing phage have all greatly advanced the experimental capacity to generate, characterize, and complement mutations within L. monocytogenes and to define functional roles of gene products. This chapter provides a brief description of the genetic tools currently available for use with L. monocytogenes. Key references are given throughout this description to provide sources for expanded details on plasmid constructions, assay conditions, and other technical aspects. The variety of genetic tools described is meant to be representative of the resources available to those interested in L. monocytogenes genetics. More widely used tools for studying expression profiles of bacteria are whole-genome DNA macro- and microarrays, which provide a comprehensive transcriptional analysis enabling researchers to view the organism as a system. Several reporter genes developed for use in other systems have proven useful for monitoring L. monocytogenes transcriptional gene regulation. Transcriptional fusions to reporter genes such as lacZ, gus, gfp, lux, and cat have all been constructed in L. monocytogenes and have been used successfully to monitor patterns of bacterial gene expression in culture and within infected cells and animals. The advantages and/or disadvantages of some of these reporter systems are discussed briefly.