Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/1998
Publication Date: N/A
Interpretive Summary: Fresh poultry is frequently contaminated with a bacteria (Campylobacter jejuni) that causes gastrointestinal disease (food poisoning) in humans. We did studies to determine how this bacteria is able to survive in the intestinal tract of chickens. We discovered that it responds to harsh environmental conditions by producing certain proteins called heat shock proteins. Further, we created a strain of this bacteria which lacks the ability to produce these proteins and is therefore unable to survive in the chicken. This observation furthers our understanding of how Campylobacter survives in the chicken and may lead to intervention strategies.
Technical Abstract: Campylobacter jejuni, a microaerophilic, gram-negative bacterium, is a common cause of gastrointestinal disease in humans. Heat-shock proteins (hsps) are a group of highly conserved, co-regulated proteins that play important roles in enabling organisms to cope with physiological stresses. The primary aim of this study was to characterize the heat shock response of C. jejuni. Twenty-four proteins were preferentially synthesized by C. jejuni immediately following heat shock. Upon immunoscreening E. coli transformants harboring a Campylobacter genomic DNA library, one recombinant plasmid was isolated that encodes a heat shock protein. The recombinant plasmid, designated pMEK20, contained an open reading frame of 1,119-bp that was capable of encoding a protein of 372 amino acids with a calculated molecular mass of 41,436 Da. The deduced amino acid sequence of the open reading frame shared similarity with DnaJ, belonging to the hsp40 family of molecular chaperones, from a number of bacteria. An E. coli DnaJ-mutant was successfully complemented with the pMEK20 recombinant plasmid as judged by the ability of bacteriophage lambda to form plaques, indicating that the C. jejuni gene encoding the 41 kDa protein is a functional homolog of the DnaJ gene from E. coli. The ability of each of two C. jejuni DnaJ mutants to form colonies at 46 C was severely retarded, indicating that DnaJ plays an important role in C. jejuni thermotolerance. Experiments revealed that a C. jejuni DnaJ mutant was unable to colonize newly hatched Leghorn chickens, suggesting that hsps play a role in vivo.