Interactions between alpha-conotoxin MI and the Torpedo marmorata receptor alpha-delta interface |
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Authors: | Cortez Leonardo Marino-Buslje Cristina de Jiménez Bonino Mirtha Biscoglio Hellman Ulf |
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Institution: | Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires Instituto de Química y Fisicoquímica Biológicas (UBA, CONICET), Junín 956 (1113), Buenos Aires, Argentina. |
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Abstract: | The muscle-type nicotinic receptor has two distinguishable acetylcholine binding sites at the alpha-gamma and alpha-delta subunit interfaces; alpha-conotoxins can bind them selectively. Moreover, we previously reported that alpha-conotoxin MI can interact with Torpedo californica and Torpedo marmorata receptors showing that conotoxins can also detect receptors from different species of the same genus L. Cortez, S.G. del Canto, F. Testai, M.B. de Jiménez Bonino, Conotoxin MI inhibits the acetylcholine binding site of the Torpedo marmorata receptor, Biochem. Biophys. Res. Commun. 295 (2002) 791-795]. Herein, to identify T. marmorata receptor regions involved in alpha-conotoxin MI binding, a photoactivatable reagent was used and labeled sites were mapped by enzymatic proteolysis, MALDI-TOF-MS and Edman degradation. alpha-Conotoxin MI binding determinants were found and studies revealed a second binding motif at the alpha/delta interface. A proposal for receptor-toxin interaction is discussed based on experimental results and docking studies. |
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Keywords: | α-CnTx α-conotoxin DMSO dimethylsulfoxide MALDI-TOF-MS matrix-assisted laser desorption/ionization time-of-flight mass spectrometry MS mass spectrometry NHS-ASA N-hydroxysuccinimidyl-4-azido salicilyc acid LBD ligand-binding domain nAChR nicotinic acetylcholine receptor |
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