PEB1, THE MAJOR CELL-BINDING FACTOR OF CAMPYLOBACTER-JEJUNI, IS A HOMOLOG OF THE BINDING-COMPONENT IN GRAM-NEGATIVE NUTRIENT TRANSPORT-SYSTEMS

The protein PEB1 (28 kDa) is a common antigen and a major cell adheren ce molecule of Campylobacter jejuni and Campylobacter coli. We created a bank of chromosomal DNA fragments of C. jejuni strain 81-176 using lambdagt11. Screening this bank in Escherichia coli Y1090 cells with a ntibody raised against purified PEB1 enabled us to isolate and to puri fy a clone with a 2.6-kilobase insert expressing an immunoreactive pro tein of 28 kDa. DNA sequencing revealed that the insert contains three complete and two partial open reading frames (ORFs), designated 5' to 3' as ORFs A-E. The peb1A gene (ORF D) contains 780 bases encoding a 259-residue polypeptide having a calculated molecular mass of 28,181 D a. The peptide sequence starting at residue 27 matches that determined from amino-terminal sequencing of mature PEB1 from C. jejuni. The fir st 26 residues contain typical signal peptidase I and II cleavage site s. The deduced amino acid composition and pl of the recombinant mature protein are similar to those determined for purified PEB1. Gene bank searches indicated significant overall homology of peb1A and ORF C wit h operons for amino acid transport systems in other Gram-negative orga nisms. peb1A is homologous to the binding components of systems such a s glnH (27.8%) and hisJ (28.9%), whereas ORF C has nearly 50% identity to glnQ and hisP. Thus, PEB1 could be involved both in binding to int estinal cells and in amino acid transport.