TY - JOUR
T1 - Molecular determinants for differential activation of the bile acid receptor from the pathogen Vibrio parahaemolyticus
AU - Zou, Angela J.
AU - Kinch, Lisa
AU - Chimalapati, Suneeta
AU - Garcia, Nalleli
AU - Tomchick, Diana R.
AU - Orth, Kim
N1 - Publisher Copyright:
© 2023 The Authors
PY - 2023/4
Y1 - 2023/4
N2 - Bile acids are important for digestion of food and antimicrobial activity. Pathogenic Vibrio parahaemolyticus senses bile acids and induce pathogenesis. The bile acid taurodeoxycholate (TDC) was shown to activate the master regulator, VtrB, of this system, whereas other bile acids such as chenodeoxycholate (CDC) do not. Previously, VtrA–VtrC was discovered to be the co-component signal transduction system that binds bile acids and induces pathogenesis. TDC binds to the periplasmic domain of the VtrA–VtrC complex, activating a DNA-binding domain in VtrA that then activates VtrB. Here, we find that CDC and TDC compete for binding to the VtrA–VtrC periplasmic heterodimer. Our crystal structure of the VtrA–VtrC heterodimer bound to CDC revealed CDC binds in the same hydrophobic pocket as TDC but differently. Using isothermal titration calorimetry, we observed that most mutants in the binding pocket of VtrA–VtrC caused a decrease in bile acid binding affinity. Notably, two mutants in VtrC bound bile acids with a similar affinity as the WT protein but were attenuated for TDC-induced type III secretion system 2 activation. Collectively, these studies provide a molecular explanation for the selective pathogenic signaling by V. parahaemolyticus and reveal insight into a host's susceptibility to disease.
AB - Bile acids are important for digestion of food and antimicrobial activity. Pathogenic Vibrio parahaemolyticus senses bile acids and induce pathogenesis. The bile acid taurodeoxycholate (TDC) was shown to activate the master regulator, VtrB, of this system, whereas other bile acids such as chenodeoxycholate (CDC) do not. Previously, VtrA–VtrC was discovered to be the co-component signal transduction system that binds bile acids and induces pathogenesis. TDC binds to the periplasmic domain of the VtrA–VtrC complex, activating a DNA-binding domain in VtrA that then activates VtrB. Here, we find that CDC and TDC compete for binding to the VtrA–VtrC periplasmic heterodimer. Our crystal structure of the VtrA–VtrC heterodimer bound to CDC revealed CDC binds in the same hydrophobic pocket as TDC but differently. Using isothermal titration calorimetry, we observed that most mutants in the binding pocket of VtrA–VtrC caused a decrease in bile acid binding affinity. Notably, two mutants in VtrC bound bile acids with a similar affinity as the WT protein but were attenuated for TDC-induced type III secretion system 2 activation. Collectively, these studies provide a molecular explanation for the selective pathogenic signaling by V. parahaemolyticus and reveal insight into a host's susceptibility to disease.
KW - bacterial pathogenesis
KW - bile acid
KW - host–pathogen interaction
KW - receptor structure–function
KW - type III secretion system
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U2 - 10.1016/j.jbc.2023.104591
DO - 10.1016/j.jbc.2023.104591
M3 - Article
C2 - 36894018
AN - SCOPUS:85151779917
SN - 0021-9258
VL - 299
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 4
M1 - 104591
ER -