Publications (2)6.96 Total impact
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Article: Botulinum neurotoxin G binds synaptotagmin-II in a mode similar to serotype B: tyrosine-1186 and lysine-1191 cause its lower affinity.
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ABSTRACT: Botulinum neurotoxins (BoNTs) block neurotransmitter release by proteolyzing SNARE proteins in peripheral nerve terminals. Entry into neurons occurs subsequent to interaction with gangliosides and a synaptic vesicle protein. Isoform I and II of synaptotagmin were shown to act as protein receptors for two of the seven BoNT serotypes, BoNT/B and BoNT/G, and for the mosaic type BoNT/DC. BoNT/B and BoNT/G exhibit a homologous binding site for synaptotagmin whose interacting part adopts helical structure upon binding to BoNT/B. Whereas the BoNT/B-synaptotagmin-II interaction has been elucidated in molecular detail, corresponding information for BoNT/G is lacking. Here we systematically mutated the synaptotagmin binding site in BoNT/G and performed a comparative binding analysis with mutants of the cell binding subunit of BoNT/B. The results suggest that synaptotagmin takes the same overall orientation in BoNT/B and BoNT/G governed by the strictly conserved central parts of the toxins' binding site. The surrounding nonconserved areas differently contribute to receptor binding. Reciprocal mutations Y1186W and L1191Y increased binding of BoNT/G approximately to the level of BoNT/B affinity suggesting a similar synaptotagmin bound state. The effects of the mutations were confirmed by studying the activity of correspondingly mutated full-length BoNTs. Based on these data molecular modeling experiments were employed to reveal an atomistic model of BoNT/G-synaptotagmin recognition. These data suggest reduced length and/or a bend in the C-terminal part of the synaptotagmin helix that forms upon contact with BoNT/G as compared with BoNT/B and are in agreement with the data of the mutational analyses.Biochemistry 05/2013; · 3.42 Impact Factor -
Article: Human synaptotagmin-II is not a high affinity receptor for botulinum neurotoxin B and G: increased therapeutic dosage and immunogenicity.
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ABSTRACT: Botulinum neurotoxins (BoNTs) inhibit neurotransmitter release by hydrolysing SNARE proteins essential for exocytosis. The synaptic vesicle protein synaptotagmin-II of rat and mouse acts as neuronal high affinity receptor for BoNT/B and BoNT/G. Here, we show that human synaptotagmin-II is not a high affinity receptor for BoNT/B and G due to a phenylalanine to leucine mutation in its luminal domain present only in humans and chimpanzees. It eliminates one of three major interactions between synaptotagmin-II and BoNT/B and hereby explains the disparity in potency of BoNT/B in humans and mice as well as the 40-fold higher dosage of rimabotulinumtoxinB versus onabotulinumtoxinA.FEBS letters 02/2012; 586(4):310-3. · 3.54 Impact Factor
