ClpB enhances thermotolerance in <i>Campylobacter jejuni</i> through protein disaggregation independent of DnaK

<i>Campylobacter jejuni</i> is a leading cause of foodborne infections worldwide and primarily transmitted to humans through the consumption of contaminated poultry meat. To enhance <i>Campylobacter</i>-associated food safety, it is critical to understand how <i>C. jejuni</i> survives during the thermal processing of poultry products. In this study, we monitored the survival of 86 <i>C</i>. <i>jejuni</i> strains during heat treatment and observed that some strains exhibited elevated heat tolerance. Notably, multilocus sequence typing clonal complex (CC)-443 and CC-607 were dominant among heat-tolerant strains, while the CC-21 strains were mostly heat-sensitive, indicating phylogenetic association with thermotolerance. We also investigated the function of heat shock chaperones in the thermotolerance of <i>C. jejuni</i>. Among several knockout mutants of heat shock chaperones, a mutant lacking <i>clpB</i> exhibited significantly lower survival than the wild type under heat treatment. Moreover, we observed a significantly higher accumulation of protein aggregates in the absence of <i>ClpB</i>, demonstrating that ClpB functions as a disaggregase during heat exposure. Additionally, ClpB from the heat-tolerant CC-443 group possessed distinct amino acid substitutions in the functional nucleotide-binding domain compared to ClpB in other CC groups. Interestingly, despite the well-known interaction of these proteins in many other bacteria, a two-hybrid assay demonstrated that ClpB of <i>C. jejuni</i> does not bind to DnaK, suggesting that <i>C. jejuni</i> may have a distinct mechanism for protein disaggregation and stress tolerance. Our findings demonstrate that ClpB plays a crucial role in the thermotolerance of <i>C. jejuni</i> through unique protein disaggregation mechanisms during poultry processing.IMPORTANCEThis study unveils a distinctive mechanism of thermotolerance involving protein disaggregation in <i>Campylobacter jejuni</i>, a major foodborne pathogen. Understanding <i>C. jejuni</i>'s ability to withstand heat stress is crucial for comprehending the occurrence of <i>Campylobacter</i> infections resulting from the consumption of contaminated poultry meat. Our research elucidates the roles of heat shock proteins, particularly ClpB, in the thermotolerance of <i>C. jejuni</i>. These findings significantly contribute to our fundamental understanding of bacterial physiology related to stress tolerance, which has important implications for public health and food safety.