Conservation, localization and expression of HopZ, a protein involved in adhesion of Helicobacter pylori

From a sarkosyl-insoluble outer membrane fraction prepared from the Helicob acter pylori strain ATCC 43504, 19 proteins could be sequenced N-terminally by Edman degradation. Oligonucleotides were deduced and used for screening of a genomic library. From the isolated genes, five code for different mem bers of a H.pylori outer membrane protein (Hop) family, Among these, the ho pZ gene was characterized in more detail. It encodes a protein which was sh own to be located at the bacterial surface by immunofluorescence studies. S equence analysis of the hopZ gene from 15 different H.pylori strains reveal ed the existence of two alleles and the possible regulation of hopZ express ion by slipped-strand mispairing within a CT dinucleotide repeat motif loca ted in the signal-peptide coding region. Among the different strains, the i nfluence of this region on the expression of HopZ was analyzed on a transla tional level by western blot analysis of bacterial extracts and immunofluor escence studies on intact cells, The protein is expressed only in those str ains in which the number of the CT dinucleotide repeats allow for an open r eading frame encoding the complete protein. Addionally the function of HopZ was investigated in an adhesion assay. The wild-type strain ATCC 43504 adh ered to human gastric epithel cells whereas a knockout mutant strain showed significantly reduced binding to the cells.