1KBA

CRYSTAL STRUCTURE OF KAPPA-BUNGAROTOXIN AT 2.3-ANGSTROM RESOLUTION

Summary for 1KBA

• Entry DOI: 10.2210/pdb1kba/pdb
• Related: 1NBT
• Descriptor: KAPPA-BUNGAROTOXIN (2 entities in total)
• Functional Keywords: toxin
• Biological source: Bungarus multicinctus (many-banded krait)
• Total number of polymer chains: 2
• Total formula weight: 14564.70

Authors

Dewan, J.C.,Grant, G.A.,Sacchettini, J.C. (deposition date: 1994-07-13, release date: 1994-12-20, Last modification date: 2024-11-06)

Primary citation

Dewan, J.C.,Grant, G.A.,Sacchettini, J.C.
Crystal structure of kappa-bungarotoxin at 2.3-A resolution.
Biochemistry, 33:13147-13154, 1994

PubMed Abstract: kappa-Neurotoxins display a very low affinity for neuromuscular receptors, but bind tightly to, and inhibit, nicotinic acetylcholine receptors in neuronal tissue such as the chick ciliary ganglia. In contrast, alpha-neurotoxins bind with high affinity and inhibit nicotinic acetylcholine receptors at the neuromuscular junction. The origin of this difference in specificity has been a long-studied question in the field. Here we report the first crystal structure of a kappa-neurotoxin, kappa-bungarotoxin. Unlike the NMR structure previously reported [Sutcliffe, M. J., Dobson, C. M., & Oswald, R. E. (1992) Biochemistry 31, 2962-2970], the present crystal structure more accurately defines the polypeptide fold and the nature of the interaction between subunits in the active dimer, which is a unique feature of the kappa-neurotoxins. The structure has been refined to R = 19.6% with X-ray diffraction data extending to a resolution of 2.3 A. There are two independent protein molecules (66 amino acid residues each) in the asymmetric unit that are arranged as a dimer with the two subunits related by a rotation of 178.6 degrees. Each subunit consists of three main-chain loops. Three of the five beta-strands of each subunit form an antiparallel beta-sheet which becomes an extended six-stranded antiparallel beta-sheet, by virtue of the approximate 2-fold symmetry of the dimer. The interactions at the dimer interface consist of six main-chain-main-chain hydrogen bonds, as well as three other hydrogen-bonding interactions involving side chains.(ABSTRACT TRUNCATED AT 250 WORDS)

PubMed: 7947721
DOI: 10.1021/bi00248a026

Experimental method

X-RAY DIFFRACTION (2.3 Å)