PhonetachykininsPeptides (PhTkP): A Diverse Family Of Tachykinin-Related Peptides From The Venom Of Phoneutria nigriventer

1,2Pimenta, A.M.C.; 1,2Rates, B.; 1,3Santoro, M.M.; 4Bloch Jr., C.; 1,2De Lima, M.E.; 5Gomes, P.C.; 5Richardson, M.; 5Cordeiro, M.N.

1 Núcleo de Biomoléculas, 2 Laboratório de Venenos e Toxinas Animais, 3 Laboratório de Enzimologia e Físico-química de Proteínas, Depto. de Bioquímica e Imunologia, ICB, UFMG, Belo Horizonte, Brazil; 4 Laboratório de Espectrometria de Massa, Embrapa-Recursos Genéticos e Biotecnologia, Brasília-DF, Brazil; 5 CPPCD, Fundação Ezequiel Dias, Belo Horizonte, Brazil.

Previous studies with venom of the spider Phoneutrianigriventer have demonstrated the presence of peptides able to provoke contractions in smooth muscle of guinea pig’s ileum, which were contained in the fraction named PhM. In the present work, the analysis by mass spectrometry (ESI-Q-ToF) of the first 15 fractions, amongst the 50 obtained through reversed phase liquid chromatography (RP-HPLC) of the crude venom of P. nigriventer, revealed the existence of peptides with molecular weights corresponding to those of the PhM fraction (850-1700 Da). The amino acid sequences from 15 of these peptides have been determined by MS/MS fragmentation using ESI-Q-ToF and MALDI-ToF/ToF. These peptides are a diverse family of isoforms which may contain 7 to 14 amino acid residues. It was found that these peptides are structurally related to the tachykinins, a ubiquous family of neuro-hormone peptides. Therefore, the observed isoforms were named as PhonetachykininPeptides (PhTkP) I to XV. Some of the longest isoforms posses a C-terminal motif (-FYGLM-_NH2) which is a molecular signature of the tachykinin family. Additionally, most of the PhTkPs share a commom scaffold containing basic and acidic residues and an N-terminal pyroglutamic acid residue (Pyr-KKDKKD). There are four main isoforms, which differ from each other by a conservative mutation (K8R) and/or by a switch at the N-terminal position (M13F). These isoforms may be C-terminally cleaved, apparently by chymotrypsin and trypsin-like enzymes present in the venom, thus, generating additional isoforms. Also, three minor isoforms were observed, being generated either by a mutation (K3N), or deletion at positions 5, 6 and 7 (K5 or K5K6D7). The data obtained in this study will certainly provide subsides to the subsequent steps of this research which envisage the solid-phase synthesis and pharmacological characterization of the PhTkPs and its synthetic analogs.

Support: CAPES, CAPES-PRODOC, FINEP, MCT-INFRA, FAPEMIG AND CNPq.

Correspondence to: brenorates@ufmg.br