TY - JOUR
T1 - Different contributions of HtrA protease and chaperone activities to Campylobacter jejuni stress tolerance and physiology
AU - Bæk, Kristoffer Torbjørn
AU - Vegge, Christina Skovgaard
AU - Skórko-Glonek, Joanna
AU - Brøndsted, Lone
PY - 2011/1
Y1 - 2011/1
N2 - The microaerophilic bacterium Campylobacter jejuni is the most common cause of bacterial food-borne infections in the developed world. Tolerance to environmental stress relies on proteases and chaperones in the cell envelope, such as HtrA and SurA. HtrA displays both chaperone and protease activities, but little is known about how each of these activities contributes to stress tolerance in bacteria. In vitro experiments showed temperature-dependent protease and chaperone activities of C. jejuni HtrA. A C. jejuni mutant lacking only the protease activity of HtrA was used to show that the HtrA chaperone activity is sufficient for growth at high temperature or under oxidative stress, whereas the HtrA protease activity is essential only under conditions close to the growth limit for C. jejuni. However, the protease activity was required to prevent induction of the cytoplasmic heat shock response even under optimal growth conditions. Interestingly, the requirement of HtrA at high temperatures was found to depend on the oxygen level, and our data suggest that HtrA may protect oxidatively damaged proteins. Finally, protease activity stimulates HtrA production and oligomer formation, suggesting that a regulatory role depends on the protease activity of HtrA. Studying a microaerophilic organism encoding only two known periplasmic chaperones (HtrA and SurA) revealed an efficient HtrA chaperone activity and proposed multiple roles of the protease activity, increasing our understanding of HtrA in bacterial physiology.
AB - The microaerophilic bacterium Campylobacter jejuni is the most common cause of bacterial food-borne infections in the developed world. Tolerance to environmental stress relies on proteases and chaperones in the cell envelope, such as HtrA and SurA. HtrA displays both chaperone and protease activities, but little is known about how each of these activities contributes to stress tolerance in bacteria. In vitro experiments showed temperature-dependent protease and chaperone activities of C. jejuni HtrA. A C. jejuni mutant lacking only the protease activity of HtrA was used to show that the HtrA chaperone activity is sufficient for growth at high temperature or under oxidative stress, whereas the HtrA protease activity is essential only under conditions close to the growth limit for C. jejuni. However, the protease activity was required to prevent induction of the cytoplasmic heat shock response even under optimal growth conditions. Interestingly, the requirement of HtrA at high temperatures was found to depend on the oxygen level, and our data suggest that HtrA may protect oxidatively damaged proteins. Finally, protease activity stimulates HtrA production and oligomer formation, suggesting that a regulatory role depends on the protease activity of HtrA. Studying a microaerophilic organism encoding only two known periplasmic chaperones (HtrA and SurA) revealed an efficient HtrA chaperone activity and proposed multiple roles of the protease activity, increasing our understanding of HtrA in bacterial physiology.
U2 - 10.1128/AEM.01603-10
DO - 10.1128/AEM.01603-10
M3 - Journal article
C2 - 21075890
SN - 0099-2240
VL - 77
SP - 57
EP - 66
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
IS - 1
ER -