Molecular Cloning and Nucleotide Sequence Determination of htrA, a Gene Encoding a 48-kDa Stress Protein of Helicobacter pylori

Abstract

The importance of the outer membrane and its pathogenesis of Helicobacter pylori in gastroduodenal disease has not fully determined. Surface-exposed proteins or those that may be exported to the surface may play an important role in the organisms’ colonization, maintenance and pathogenic action on gastric epithelial cells. It has previously been reported that H. pylori possesses three major outer memb 31 kDa [6] and which have all been shown to be highly immunogenic [2]. Acid extractable preparations and ¹²⁵ I surface labelling of H. pylori has demonstrated several variable proteins, including a 48-kDa antigen [6, 8]. Genotypic diversity, already described for this organism, may allow variation in antigentic determinants on the cell surface [7]. Such a phenomenon may not only explain the presence of variable proteins on the membrane but may play a role in assisting the organism in evading the host’s immune system. This led us to investigate membrane-associated proteins from H. pylori. The colning of genes encode these proteins in Escherichia coli should provide information not only on virulence, but both phenotypic and genotypic interstrain variation and possible regulatory sequences. We isolated a crude membrane prepration to which polyclonal antibody was prepared and used to screen a lambda (λ) EMBL 3 H. pylori genomic library.