Influence of a NH2-terminal extension on the activity of KTX2, a K+ channel blocker purified from Androctonus australis scorpion venom

C Legros; E Feyfant; F Sampieri; H Rochat; P E Bougis; M F Martin-Eauclaire

doi:10.1016/s0014-5793(97)01177-0

Influence of a NH2-terminal extension on the activity of KTX2, a K+ channel blocker purified from Androctonus australis scorpion venom

FEBS Lett. 1997 Nov 3;417(1):123-9. doi: 10.1016/s0014-5793(97)01177-0.

Authors

C Legros¹, E Feyfant, F Sampieri, H Rochat, P E Bougis, M F Martin-Eauclaire

Affiliation

¹ Laboratoire de Biochimie, Ingénierie des Protéines, UMR 6560 du Centre National de la Recherche Scientifique, Institut Fédératif Jean Roche, Faculté de Médecine Nord, Marseille, France.

PMID: 9395089
DOI: 10.1016/s0014-5793(97)01177-0

Abstract

A cDNA encoding a short polypeptide blocker of K+ channels, kaliotoxin 2 (KTX2), from the venom of the North African scorpion Androctonus australis was expressed in the periplasmic space of Escherichia coli. KTX2 was produced as a fusion protein with the maltose binding protein followed by the recognition site for factor Xa or enterokinase preceding the first amino acid residue of the toxin. The fully refolded recombinant KTX2 (rKTX2) was obtained (0.15-0.30 mg/l of culture) and was indistinguishable from the native toxin according to chemical and biological criteria. An N-extended analogue of KTX2 exhibiting three additional residues was also expressed. This analogue had 1000-fold less affinity for the 125I-kaliotoxin binding site on rat brain synaptosomes than KTX2. Conformational models of KTX2 and its mutant were designed by amino acid replacement using the structure of agitoxin 2 from Leiurus quinquestriatus as template, to try to understand the decrease in affinity for the receptor.

MeSH terms

ATP-Binding Cassette Transporters*
Amino Acid Sequence
Animals
Binding Sites
Carrier Proteins / genetics
Cloning, Molecular
Escherichia coli
Escherichia coli Proteins*
Factor Xa / metabolism
Gene Expression
Genetic Vectors
Maltose-Binding Proteins
Models, Molecular
Molecular Sequence Data
Molecular Structure
Monosaccharide Transport Proteins*
Periplasmic Binding Proteins*
Potassium Channel Blockers*
Rats
Recombinant Fusion Proteins / biosynthesis
Recombinant Fusion Proteins / chemistry
Recombinant Fusion Proteins / metabolism
Scorpion Venoms / biosynthesis
Scorpion Venoms / chemistry
Scorpion Venoms / genetics
Scorpion Venoms / metabolism*
Scorpions
Sequence Homology, Amino Acid
Structure-Activity Relationship
Synaptosomes / metabolism

Substances

ATP-Binding Cassette Transporters
Carrier Proteins
Escherichia coli Proteins
MalE protein, E coli
Maltose-Binding Proteins
Monosaccharide Transport Proteins
Periplasmic Binding Proteins
Potassium Channel Blockers
Recombinant Fusion Proteins
Scorpion Venoms
kaliotoxin
maltose transport system, E coli
Factor Xa