NUCLEOTIDE-SEQUENCE AND CHARACTERIZATION OF PEB4A ENCODING AN ANTIGENIC PROTEIN IN CAMPYLOBACTER-JEJUNI

The 29-kDa protein PEB4, a major antigen of Campylobacter jejuni, is p resent in all C. jejuni strains tested and elicits an antibody respons e in infected patients. By screening a lambda gt11 library of chromoso mal DNA fragments of C. jejuni strain 81-176 in Escherichia coli Y1090 cells with antibody raised against purified PEB4, a recombinant phage with a 2-kb insert expressing an immunoreactive protein of 29 kDa was isolated. DNA sequence analysis revealed that the insert contains two complete open reading frames ORF-A and ORF-B. ORF-A (peb4A) encodes a 273-residue protein with a calculated molecular mass of 30,460 dalton s. The deduced amino acid sequence, composition and pl of the recombin ant mature protein are similar to those determined for purified PEB4. The first 21 residues resemble a signal peptide. Gene bank searches in dicated 33.7% identity with protein export protein PrsA of Bacillus su btilis and 23.8% identity with protease maturation protein precursor P rtM of Lactococcus lactis. PCR experiments indicate that peb4A is high ly conserved among C. jejuni strains. ORF-B begins 2 bp after the last codon of peb4A and encodes a putative protein of 353 residues with 63 .4% identity with E. coli fructose 1,6-biphosphate aldolase. The seque nce arrangement suggests that these two genes form an operon.