A lysine rich C-terminal tail is directly involved in the toxicity of CSTX-1, a neurotoxic peptide from the venom of the spider Cupiennius salei.
CSTX-1 (74 amino acids, 8,352.62 Da) is a potent neurotoxin from the venom of Cupiennius salei. With the monoclonal antibody 9H3 against CSTX-1, we identified two similar peptides by Western blot analysis. These two peptides were purified by RP-HPLC: CSTX-2a (61 amino acids, 6865.75 Da) and CSTX-2b (60 amino acids, 6709.57 Da). Using ESI-MS analysis and sequencing we verified that CSTX-2a is a truncated version of CSTX-1. CSTX-2b differs from CSTX-2a by the absence of Arg61. Toxicity of CSTX-1, CSTX-2a, and CSTX-2b to Drosophila melanogaster showed that the absence of the last 13 amino acids of CSTX-1 results in a seven-fold activity loss. CSTX-2b, which lacks Arg61 is 190-fold less toxic. We conclude that the C-terminal part of CSTX-1, especially Arg61, is essential for the expression of toxicity. CSTX-1 is degraded to CSTX-2a and CSTX-2b by proteases that are released from venom gland cells by apocrine secretion.
Kuhn-Nentwig
L
L
Institute of Zoology, University of Bern, Switzerland. lucia.kuhn@zos.unibe.ch
Schaller
J
J
Kämpfer
U
U
Imboden
H
H
Malli
H
H
Nentwig
W
W
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D001681:Biological Assay; D004331:Drosophila melanogaster; D010450:Endopeptidases / Q000378:metabolism; D004765:Enteropeptidase / Q000378:metabolism; D015951:Factor Xa / Q000378:metabolism; D008239:Lysine / Q000737:chemistry*; D008969:Molecular Sequence Data; D009498:Neurotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity; D030162:Reptilian Proteins; D017421:Sequence Analysis / Q000379:methods; D013111:Spider Venoms / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D013112:Spiders
D000596:Amino Acids; C412284:CSTX-2a protein, Cupiennius salei; D009498:Neurotoxins; D010455:Peptides; D030162:Reptilian Proteins; D013111:Spider Venoms; D010450:Endopeptidases; D015951:Factor Xa; D004765:Enteropeptidase; D008239:Lysine