Comparative roles of clpA and clpB in the survival of S. Typhimurium under stress and virulence in poultry

Abstract

By assisting in the proteolysis, disaggregation and refolding of the aggregated proteins, Caseinolytic proteases (Clps) enhance the cellular survival under stress conditions. In the current study, comparative roles of two such Clps, ClpA (involved in proteolysis) and ClpB (involved in protein disaggregation and refolding) in the survival of Salmonella Typhimurium (S. Typhimurium) under different stresses and in virulence have been investigated. clpA and clpB gene deletion mutant strains (∆clpA and ∆clpB) of S. Typhimurium have been hypersensitive to 42 °C, HOCl and paraquat. However, the ∆clpB strain was comparatively much more susceptible (p < 0.001) to the above stresses than ∆clpA strain. ∆clpB strain also showed reduced survival (p < 0.001) in poultry macrophages. The hypersusceptibilities of ∆clpB strain to oxidants and macrophages were restored in plasmid based complemented (∆clpB + pclpB) strain. Further, the ∆clpB strain was defective for colonization in the poultry caecum and showed decreased dissemination to the spleen and liver. Our findings suggest that the role of ClpB is more important than the role of ClpA for the survival of S. Typhimurium under stress and colonization in chickens.

Role of ClpB From Corynebacterium crenatum in Thermal Stress and Arginine Fermentation

“…Athar et al (2018) also certified that ClpB performs important functions during low-pH stress response. Many previous observations showed that ClpB contributes to the survival of bacteria during heat stress (Squires et al, 1991;Athar et al, 2018;Sangpuii et al, 2018). Our results showed (Figure 3B) that the activity of ClpB was relatively unaltered at 30-40 • C and decreased evidently at 25 and 45 • C. ATPase activity decreased by only 7% at 40 • C relative to the highest value (at 30 • C), which revealed that ClpB efficiently functioned during heat stress, but not during cold stress.…”

“… Athar et al (2018) also certified that ClpB performs important functions during low-pH stress response. Many previous observations showed that ClpB contributes to the survival of bacteria during heat stress ( Squires et al, 1991 ; Athar et al, 2018 ; Sangpuii et al, 2018 ). Our results showed ( Figure 3B ) that the activity of ClpB was relatively unaltered at 30–40°C and decreased evidently at 25 and 45°C.…”

“…The differences of growth were obvious through liquid growth analyses ( Figure 5B), and C. crenatum dnaK and C. crenatum dnaK clpB showed the weakest growth rate, indicating that ClpB and DnaK contribute to thermal stress tolerance. Compared with the wild type of Salmonella typhimurium, clpB strains did not show any sensitivity to a temperature of 37 • C but were hypersusceptible (p < 0.001) to a temperature of 42 • C (Sangpuii et al, 2018). When subjected to high temperature (50 • C), the survival of the clpB mutant of Francisella tularensis was compromised, whereas the CFU of the wild-type strains did not drop significantly (Athar et al, 2018).…”

“…ClpB plays a vital role in the survival of microorganisms during stressful conditions (Squires et al, 1991;Athar et al, 2018;Sangpuii et al, 2018). In general, bacterial ClpB cooperates with DnaK cochaperone to refold and rescue aggregated proteins, thereby helping cells survive under stressful conditions (Lupoli et al, 2016).…”

“…Proteolysis is essential under conditions where many misfolded and damaged proteins are likely to accumulate, particularly oxidizing environments, non-physiological pH, or elevated temperatures (Raivio, 2018). The survival rate of bacteria decreases tremendously without ClpB when cells are under various stressful conditions, and ClpB is involved in supporting the virulence of some bacterial pathogens (Squires et al, 1991;Athar et al, 2018;Sangpuii et al, 2018). Multiple enzymes of the central carbon metabolism are potential substrates of ClpB.…”