Scorpion toxins from Buthus martensii Karsch all possess a predicted alpha-tight-turn

We have purified a new toxin (BmK 17[4]) from Asian scorpion (Buthus martensii Karsch) venom that possesses a distinctive structural motif in its N-terminal (positions 8-12) that is similarly found in two other previously described alpha-like toxins. BmK 17[4] prolongs action potentials (APs) in frog nerve and was purified using gel filtration, ion exchange, fast protein liquid chromatography (FPLC), and high-performance liquid chromatography (HPLC). BmK 17[4] significantly prolonged frog APs but it did not alter APs from an insect ventral nerve cord at similar doses. When applied to voltage-clamped frog muscle single fibers, BmK 17[4] prolonged fast inactivation. Because the polypeptide prolongs APs when both K+ and Ca2+ channels were blocked, BMK 17[4] acts to selectively alter Na+ channel inactivation. The N-terminal sequence of BmK 17[4] was found to be VRDAYIAKPENCVYXC --. The molar mass of BmK 17[4] was determined by LC/MS/MS to be 7097 Daltons. The N- terminal motif (KPENC), which introduces a reverse turn in residues 8-12, does not appear in previously characterized BmK alpha-toxins and may be characteristic of alpha-like toxins. Sequence similarity database searches were used to test whether the N-terminal sequences of alpha-like polypeptide toxins from B. martensii Karsch possess a distinctive structural motif in its 5-residue reverse turn (alpha-turn) that is conserved. Sequence similarities with putative polypeptides encoded by cDNAs obtained from a cDNA library [Zhu, S. Y., Li, W. X., Zenq, X. C., et al. (2000) Nine novel precursors of Buthus martensii scorpiox alpha-toxin homologues. Toxicon 38, 1653-1661] from BmK venom glands showed that an active polypeptide toxin cleaved from the putative propolypeptide toxin BmK M9 is likely identical to BmK 17[4]. Sequence comparisons with toxins and putative toxins from B. martensii Karsch and other species revealed that a group of these toxins possess a common structural motif in their alpha-turn. A neighbor-joining phylogenetic analysis suggests that there are two phylogenetic sister groups of related BmK polypeptides; one possesses the KPENC motif and the other possesses a modifed version (KPHNC) of it.

Medienart:

Artikel

Erscheinungsjahr:

2003

Erschienen:

2003

Enthalten in:

Zur Gesamtaufnahme - volume:37

Enthalten in:

Cell biochemistry and biophysics - 37(2003), 3 vom: 22., Seite 169-86

Sprache:

Englisch

Beteiligte Personen:

Hahin, Richard [VerfasserIn]
Chen, Ziyi [VerfasserIn]
Wang, Danhui [VerfasserIn]
Reddy, Giridher [VerfasserIn]
Mao, Long [VerfasserIn]

Themen:

9DLQ4CIU6V
9NEZ333N27
Cations
Journal Article
Peptides
Proline
Scorpion Venoms
Sodium
Sodium Channels

Anmerkungen:

Date Completed 26.09.2003

Date Revised 06.11.2019

published: Print

Citation Status MEDLINE

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM124005004