MOLECULAR CHARACTERIZATION OF A CAMPYLOBACTER-JEJUNI 29-KILODALTON PERIPLASMIC BINDING-PROTEIN

Campylobacter jejuni, a gram-negative, microaerophilic, spiral bacteri um, is a common cause of human gastrointestinal disease. Although inve stigators commonly use C. jejuni glycine-hydrochloride extracts in ass ays to determine the products that promote the binding of the organism to eukaryotic cells, the proteins contained within these extracts rem ain ill defined. Characterization of these proteins will provide a bet ter understanding of C. jejuni gene regulation and organization, An an tiserum was raised against a C. jejuni 29-kDa gel-purified protein det ected in glycine-hydrochloride extracts, This antiserum was used to sc reen an expression library of C. jejuni, A reactive clone that contain ed an open reading frame of 256 amino acids was identified, The cloned gene was transcribed and translated, and the product was exported to the periplasmic space in Escherichia coli XL1-Blue, The translated C. jejuni product, designated P29, exhibited significant similarity to th e histidine and lysine-arginine-ornithine periplasmic binding proteins (HisJ and LAO, respectively) of Salmonella typhimurium. The C. jejuni gene encoding the P29 protein complemented an S. typhimurium HisJ mut ant but not a LAO mutant when provided in trans. These data suggest th at the C. jejuni gene encoding the P29 protein is a homolog of the S. typhimurium hisJ gene.