Abstract
Bordetella resistance to killing (BrkA) is a Type V autotransporter found in the outer membrane of Bordetella pertussis, the bacterium responsible for whooping cough. Previous work by Garcia et al. suggested that expression of BrkA in Escherichia coli may confer heat tolerance via a DegP-dependent mechanism. DegP is a temperature-dependent serine protease responsible for degrading misfolded periplasmic proteins; its expression is upregulated by the CpxAR two-component envelope stress response system under conditions of envelope stress. In this study, we investigated the effect of BrkA expression on envelope stress by measuring CpxAR activation using a luminescence (lux) reporter assay and assessed cell survival using optical density-based heat tolerance assays at 37℃ and 42℃. The luminescence assay demonstrated that BrkA expression did not activate the CpxAR response system. Furthermore, OD600 measurements revealed no enhanced heat tolerance in BrkA-expressing E. coli. Overall, our findings show that BrkA does not activate the CpxAR response system, which indicates that BrkA does not induce detectable envelope stress. This study provides insight into how BrkA is efficiently maintained in the membrane of B. pertussis.