TY - JOUR
T1 - Congenital chloride-losing diarrhea causing mutations in the STAS domain result in misfolding and mistrafficking of SLC26A3
AU - Dorwart, Michael R.
AU - Shcheynikov, Nikolay
AU - Baker, Jennifer M R
AU - Forman-Kay, Julie D.
AU - Muallem, Shmuel
AU - Thomas, Philip J.
PY - 2008/3/28
Y1 - 2008/3/28
N2 - Congenital chloride-losing diarrhea (CLD) is a genetic disorder causing watery stool and dehydration. Mutations in SLC26A3 (solute carrier 26 family member 3), which functions as a coupled Cl-/HCO3 - exchanger, cause CLD. SLC26A3 is a membrane protein predicted to contain 12 transmembrane-spanning α-helices and a C-terminal STAS (sulfate transporters and anti-sigma-factor) domain homologous to the bacterial anti-sigma-factor antagonists. The STAS domain is required for SLC26A3 Cl -/HCO3- exchange function and for the activation of cystic fibrosis transmembrane conductance regulator by SLC26A3. Here we investigate the molecular mechanism(s) by which four CLD-causing mutations (ΔY526/7, I544N, I675/6ins, and G702Tins) in the STAS domain lead to disease. In a heterologous mammalian expression system biochemical, immunohistochemical, and ion transport experiments suggest that the four CLD mutations cause SLC26A3 transporter misfolding and/or mistrafficking. Expression studies with the isolated STAS domain suggest that the I675/6ins and G702Tins mutations disrupt the STAS domain directly, whereas limited proteolysis experiments suggest that the ΔY526/7 and I544N mutations affect a later step in the folding and/or trafficking pathway. The data suggest that these CLD-causing mutations cause disease by at least two distinct molecular mechanisms, both ultimately leading to loss of functional protein at the plasma membrane.
AB - Congenital chloride-losing diarrhea (CLD) is a genetic disorder causing watery stool and dehydration. Mutations in SLC26A3 (solute carrier 26 family member 3), which functions as a coupled Cl-/HCO3 - exchanger, cause CLD. SLC26A3 is a membrane protein predicted to contain 12 transmembrane-spanning α-helices and a C-terminal STAS (sulfate transporters and anti-sigma-factor) domain homologous to the bacterial anti-sigma-factor antagonists. The STAS domain is required for SLC26A3 Cl -/HCO3- exchange function and for the activation of cystic fibrosis transmembrane conductance regulator by SLC26A3. Here we investigate the molecular mechanism(s) by which four CLD-causing mutations (ΔY526/7, I544N, I675/6ins, and G702Tins) in the STAS domain lead to disease. In a heterologous mammalian expression system biochemical, immunohistochemical, and ion transport experiments suggest that the four CLD mutations cause SLC26A3 transporter misfolding and/or mistrafficking. Expression studies with the isolated STAS domain suggest that the I675/6ins and G702Tins mutations disrupt the STAS domain directly, whereas limited proteolysis experiments suggest that the ΔY526/7 and I544N mutations affect a later step in the folding and/or trafficking pathway. The data suggest that these CLD-causing mutations cause disease by at least two distinct molecular mechanisms, both ultimately leading to loss of functional protein at the plasma membrane.
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U2 - 10.1074/jbc.M704328200
DO - 10.1074/jbc.M704328200
M3 - Article
C2 - 18216024
AN - SCOPUS:43749089149
SN - 0021-9258
VL - 283
SP - 8711
EP - 8722
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 13
ER -