NOVEL INSECTICIDAL PEPTIDES FROM TEGENARIA-AGRESTIS SPIDER VENOM MAY HAVE A DIRECT EFFECT ON THE INSECT CENTRAL-NERVOUS-SYSTEM

Fractionation of venom from an agelenid spider, Tegenaria agrestis, re sulted in the isolation of a family of three peptides with potent inse cticidal activity. These peptide toxins, TaITX-1, -2, and -3, whose se quences were revealed from cloned cDNAs, each consist of 50 amino acid residues, six of which are cysteines, They appear to be amidated at t heir C-termini and exhibit greater than 90% sequence identity. Unlike other reported spider toxins, the TaI toxins are processed front precu rsors containing no propeptide sequences. In lepidopteran larvae and c orn rootworm beetles, the insecticidal Tegenaria toxins cause an unusu al excitatory symptomatology with 50% paralytic doses ranging from 0.2 3 to 2.6 nmol/g. In a series of electrophysiological experiments perfo rmed in house fly larvae, these toxins caused an elevated rate of firi ng from central nervous system neurons. No significant effects were fo und when any peripheral sensory or motor systems were examined. Thus, it appears that the TaI toxins may act in a fashion not previously rep orted for insecticidal peptide toxins; they may act directly on the in sect central nervous system. (C) 1998 Wiley-Liss, Inc.