The thermophilic Campylobacters are enteropathogenic for humans. We recently showed that Omp50 is a
Campylobacter species-specific porin produced in
Campylobacter jejuni and
Campylobacter lari but not in
Campylobacter coli. In the present study, we investigated regulation of the
omp50 gene and found that its expression in
C. jejuni was temperature-dependent, but independent of growth phase or medium viscosity. The use of RT-PCR and
omp50lacZ fusions showed that growth temperature control occurred at the transcriptional level. The promoter and the coding sequence were cloned in an
Escherichia coli–
Campylobacter shuttle plasmid and transferred to
E. coli and to a
C. jejuni Omp50-deficient strain. Regulation of
omp50 gene expression by growth temperature was observed in the recombinant
C. jejuni strain, but not in
E. coli. The same regulation was also observed in wild-type
C. lari strains and in a
C. coli strain supplemented by the plasmid, suggesting that
omp50 expression is controlled by a mechanism conserved among
Campylobacter species.