ABSTRACT
This chapter describes the cloning and expression of the urease genes of Helicobacter pylori. It argues that the urease gene cluster of the organism, as well as sharing certain features with those of other ureolytic bacteria, possesses certain characteristics unique unto itself. The chapter discusses the use of molecular biological techniques: first, to construct isogenic urease-negative mutants of H. pylori and, second, to type H. pylori isolates based on differences in the nucleotide sequence of regions of the urease gene cluster known to vary between isolates. H. pylori produce a urease that is interesting both from a biochemical as well as a functional standpoint. The larger subunit from H. pylori urease showed similar similarities with the largest of three subunits from Proteus mirabilis, Morganella morganii, and Klebsiella aerogenes ureases and to the jack bean urease subunit. The possibility that the expression of H. pylori urease might be influenced by the available nitrogen has been largely ignored.
