The interaction between syntaxin 1A and cystic fibrosis transmembrane conductance regulator Cl- channels is mechanistically distinct from syntaxin 1A-SNARE interactions.
Syntaxin 1A binds to and inhibits epithelial cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channels and synaptic Ca(2+) channels in addition to participating in SNARE complex assembly and membrane fusion. We exploited the isoform-specific nature of the interaction between syntaxin 1A and CFTR to identify residues in the H3 domain of this SNARE (SNARE motif) that influence CFTR binding and regulation. Mutating isoform-specific residues that map to the surface of syntaxin 1A in the SNARE complex led to the identification of two sets of hydrophilic residues that are important for binding to and regulating CFTR channels or for binding to the syntaxin regulatory protein Munc-18a. None of these mutations affected syntaxin 1A binding to other SNAREs or the assembly and stability of SNARE complexes in vitro. Conversely, the syntaxin 1A-CFTR interaction was unaffected by mutating hydrophobic residues in the H3 domain that influence SNARE complex stability and Ca(2+) channel regulation. Thus, CFTR channel regulation by syntaxin 1A involves hydrophilic interactions that are mechanistically distinct from the hydrophobic interactions that mediate SNARE complex formation and Ca(2+) channel regulation by this t-SNARE.
Ganeshan
Radhika
R
Department of Physiology and Biophysics, Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA.
Di
Anke
A
Nelson
Deborah J
DJ
Quick
Michael W
MW
Kirk
Kevin L
KL
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002460:Cell Line; D018118:Chloride Channels / Q000378:metabolism; D006224:Cricetinae; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry / Q000502:physiology*; D004594:Electrophysiology; D005260:Female; D006801:Humans; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009865:Oocytes / Q000502:physiology; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D050600:SNARE Proteins; D050827:Syntaxin 1; D014162:Transfection; D033921:Vesicular Transport Proteins; D014981:Xenopus
D000954:Antigens, Surface; C505032:CFTR protein, human; D002352:Carrier Proteins; D018118:Chloride Channels; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D050766:Qb-SNARE Proteins; D050767:Qc-SNARE Proteins; D011993:Recombinant Fusion Proteins; C100493:SNAP23 protein, human; D050600:SNARE Proteins; C494212:STX1A protein, human; C107017:Snap23 protein, mouse; C494214:Stx1a protein, mouse; D050827:Syntaxin 1; D033921:Vesicular Transport Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator