Russian Journal of Bioorganic Chemistry, Vol. 25, No. 7, 1999, š . 477

Cloning and Structure Determination of the -Latrocrustoxin Gene from the Black Widow Spider Venom

V. N. Danilevich, 1 S. A. Lukyanov, and E. V. Grishin

Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, ul. Miklukho-Maklaya 16/10, GSP-7, Moscow , 117871 Russia

Abstract: The primary structure of the crusta gene encoding -latrocrustxin (-LCT), a high molecular mass neurotoxin specific to crustaceans, was determined in the black widow spider Latrodectus mactans tredicimguttatus genome. The total length of the sequenced DNA was 4693 bp. The structural part of the black widow spider chromosome gene encoding -LCT does not contain introns. The sequenced DNA contains a single extended open reading frame (4185 bp) and encodes a protein precursor of -LCT, comprising 1395 aa. We assume the Met residue at position –10 relative to the N-terminal residue of Glu1 of the mature toxin to be the first one in the protein precursor. The calculated molecular mass of the precursor (156–147 Da) exceeds that of the mature toxin (~120 kDa) by ~30 kDa. These data are in agreement with the notion that over the course of maturation the protein precursor undergoes double processing—cleavage of a decapeptide from the N-terminal part and of a ~200-aa fragment from the C-terminal part. -LCT displayed a number of imperfect ankyrin-like repeats and areas of structural homology with latrotoxins studied earlier; the highest homology degree (62%) was revealed with -latroinsectotoxin (-LIT).

Key words: neurotoxin, Latrodectus, genomic DNA, PCR amplification, nucleotide sequence, deduced amino acid sequence