Genetic Systems in Pathogenic Neisseriae

This chapter discusses the genetic systems in pathogenic Neisseriae. Members of the genus Neisseria are gram-negative diplococci that inhabit the human body. Two members of this genus are important human pathogens: Neisseria gonorrhoeae (the gonococcus, GC) and Neisseria meningitides. The use of genetic methods has gained popularity in investigations concerning the biology of the Neisseriae, because the tools to conduct molecular genetic studies have begun to be developed. This chapter discusses what is known about the naturally occurring gene transfer systems in the pathogenic Neisseriae and how these systems are used to address biological questions. A facet of neisserial genetics is the high degree of cytosine methylation found in the chromosomal DNA of these bacteria. This high level of cytosine methylation necessitates the use of Escherichia coli strains that do not restrict N-methylcytosine DNA when cloning from Neisseriae. Only when cloned into E. coli is the regulation relieved and the activity expressed.