toxin BeKm from the scorpion Buthus eupeus

Scorpion toxin BeKm is specific blocker of hERG1 potassium channels.

Inverse active site of scorpion toxin BeKm

Bartels C., Xia T.-H., Billeter M., Guntert P. & Wuthrich K.
The program XEASY for computer-supported NMR spectral analysis
of biological macromolecules,
J. Biomol. NMR (1995) 6, 1-10.

The program XEASY for computer-supported NMR spectral analysis of biological macromolecules.

The new program DYANA (DYnamics Algorithm for Nmr Applications) for efficient
calculation of three-dimensional protein and nucleic acid structures from
distance constraints and torsion angle constraints collected by nuclear
magnetic resonance (NMR) experiments performs simulated annealing by molecular
dynamics in torsion angle space and uses a fast recursive algorithm to
integrate the equations of motions. Torsion angle dynamics can be more
efficient than molecular dynamics in Cartesian coordinate space because of the
reduced number of degrees of freedom and the concomitant absence of
high-frequency bond and angle vibrations, which allows for the use of longer
time-steps and/or higher temperatures in the structure calculation. It also
represents a significant advance over the variable target function method in
torsion angle space with the REDAC strategy used by the predecessor program
DIANA. DYANA computation times per accepted conformer in the "bundle" used to
represent the NMR structure compare favorably with those of other presently
available structure calculation algorithms, and are of the order of 160 seconds
for a protein of 165 amino acid residues when using a DEC Alpha 8400 5/300
computer. Test calculations starting from conformers with random torsion angle
values further showed that DYANA is capable of efficient calculation of
high-quality protein structures with up to 400 amino acid residues, and of
nucleic acid structures.

Guntert P., Mumenthaler C. & Wuthrich K.
Torsion angle dynamics for NMR structure calculation with
new program DYANA,
J. Mol. Biol. (1997) 273, 283-298.

Torsion angle dynamics for NMR structure calculation with the new program DYANA.

Schaumann T., Braun W. & Wuthrich K. (1990) The
program FANTOM for energy refinement of polypeptides and
proteins using a Newton-Raphson minimizer in torsion
angle space,
Biopolymers 29, 679-694.

MOLMOL is a molecular graphics program for display, analysis, and manipulation
of three-dimensional structures of biological macromolecules, with special
emphasis on nuclear magnetic resonance (NMR) solution structures of proteins
and nucleic acids. MOLMOL has a graphical user interface with menus, dialog
boxes, and on-line help. The display possibilities include conventional
presentation, as well as novel schematic drawings, with the option of combining
different presentations in one view of a molecule. Covalent molecular
structures can be modified by addition or removal of individual atoms and
bonds, and three-dimensional structures can be manipulated by interactive
rotation about individual bonds. Special efforts were made to allow for
appropriate display and analysis of the sets of typically 20-40 conformers that
are conventionally used to represent the result of an NMR structure
determination, using functions for superimposing sets of conformers,
calculation of root mean square distance (RMSD) values, identification of
hydrogen bonds, checking and displaying violations of NMR constraints, and
identification and listing of short distances between pairs of hydrogen atoms.

Koradi R., Billiter M. & Wutrich, K (1996) MOLMOL:
a program for display and analysis of macromolecular
structures,
J. Mol. Graphics 14, 51-55.

MOLMOL: a program for display and analysis of macromolecular structures.

The isolation of the peptide inhibitor of M-type K(+) current, BeKm-1, from the
venom of the Central Asian scorpion Buthus eupeus has been described previously
(Fillipov A. K., Kozlov, S. A., Pluzhnikov, K. A., Grishin, E. V., and Brown,
D. A. (1996) FEBS Lett. 384, 277-280). Here we report the cloning, expression,
and selectivity of BeKm-1. A full-length cDNA of 365 nucleotides encoding the
precursor of BeKm-1 was isolated using the rapid amplification of cDNA ends
polymerase chain reaction technique from mRNA obtained from scorpion telsons.
Sequence analysis of the cDNA revealed that the precursor contains a signal
peptide of 21 amino acid residues. The mature toxin consists of 36 amino acid
residues. BeKm-1 belongs to the family of scorpion venom potassium channel
blockers and represents a new subgroup of these toxins. The recombinant BeKm-1
was produced as a Protein A fusion product in the periplasm of Escherichia
coli. After cleavage and high performance liquid chromatography purification,
recombinant BeKm-1 displayed the same properties as the native toxin. Three
BeKm-1 mutants (R27K, F32K, and R27K/F32K) were generated, purified, and
characterized. Recombinant wild-type BeKm-1 and the three mutants partly
inhibited the native M-like current in NG108-15 at 100 nm. The effect of the
recombinant BeKm-1 on different K(+) channels was also studied. BeKm-1
inhibited hERG1 channels with an IC(50) of 3.3 nm, but had no effect at 100 nm
on hEAG, hSK1, rSK2, hIK, hBK, KCNQ1/KCNE1, KCNQ2/KCNQ3, KCNQ4 channels, and
minimal effect on rELK1. Thus, BeKm-1 was shown to be a novel specific blocker
of hERG1 potassium channels.

Korolkova YV, Kozlov SA, Lipkin AV, Pluzhnikov KA, Hadley JK, Filippov AK, Brown DA,
Angelo K, Strobaek D, Jespersen T, Olesen SP, Jensen BS, Grishin EV.
An ERG channel inhibitor from the scorpion Buthus eupeus.
J. Biol. Chem. 2001 Mar 30;276(13):9868-76

An ERG channel inhibitor from the scorpion Buthus eupeus.

Solution Structure Of Herg-Specific Scorpion Toxin Bekm-1

BeKm-1 toxin precursor [Mesobuthus eupeus]

potassium channel blocker pMeKTx12-1 [Mesobuthus eupeus]

RecName: Full=Potassium channel toxin gamma-KTx 2.1; AltName: Full=Neurotoxin BeKm-1; Flags: Precursor [Mesobuthus eupeus]

1H Chemical Shift Assignments for toxin BeKm from the Scorpion Buthus eupeus

simulated annealing combined with torsion angle dynamics