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Molecular basis of the mammalian potency of the scorpion α‐like toxin, BmK M1
Author(s) -
Liu Li-Hui,
Bosmans Frank,
Maertens Chantal,
Zhu Ron-Han,
Wang Da-Cheng,
Tytgat Jan
Publication year - 2005
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.04-2485fje
Subject(s) - scorpion toxin , mutagenesis , mutant , amino acid , toxin , scorpion , scorpion venoms , peptide , circular dichroism , biology , biochemistry , chemistry , venom , gene
In‐depth structure‐function studies of voltage‐gated Na + channels and peptide toxins are continuously increasing our understanding of their interaction. In this study, an effective yeast expression system was used to study the role of 14 N‐ and C‐terminal residues from the α‐like toxin BmK M1 from the Chinese scorpion Buthus martensii Karsch. With the use of site‐directed mutagenesis, all of these residues were individually substituted by one or more amino acids, resulting in a total of 19 mutants. These were then subjected to a bioassay on mice, an elaborate electrophysiological characterization on three cloned voltage‐gated Na + channels (Na v 1.2, Na v 1.5, and para), and a circular dichroism analysis. Our results reveal large mutant‐dependent differences that emphasize important and specific roles for the studied residues. By mutating single amino acids, we were able to redirect the α‐like characteristics of BmK M1 (active on both mammals and insects) to either much higher mammal specificity or, in a few cases, total insect specificity. This study therefore represents a thorough mapping and elucidation of three epitopes that underlie the molecular basis of the mammalian and insecticidal potency of the scorpion α‐like toxin, BmK M1 on voltage‐gated Na + channels.