Linked Life Data

9201909

Source:http://linkedlifedata.com/resource/pubmed/id/9201909

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
25
pubmed:dateCreated
1997-7-21
pubmed:abstractText
Dendrotoxin K (DTXK) is a 57-residue protein from mamba venom that blocks certain non-inactivating, voltage-activated K+ currents in neurones. In order to pinpoint the residues responsible for its specificity, structure-activity relations of DTX(K) were investigated by mutagenesis. A previously cloned gene encoding this toxin [Smith et al. (1993) Biochemistry 32, 5692-5697] was used to make single mutations; after expression in Escherichia coli as fusion proteins and enzymatic cleavage of the conjugates isolated from the periplasmic space, nine toxins were purified. Structural analysis of the native DTXK and representative mutants by circular dichroism showed that no significant differences were detectable in their folded structures. The biological activity of the mutants, which contained alterations of positively charged and other amino acids, was determined from their abilities to compete for the binding of 125I-labeled DTX(K) to K+ channels in synaptic plasma membranes from rat cerebral cortex. Mutants with residues substituted in the alpha-helix near the C-terminus (R52A or R53A) yielded binding parameters similar to those of wild-type and native DTX(K). In the case of the beta-turn (residues 24-28), however, altering single amino acids reduced binding to the high-affinity site of K+ channels, with the rank order of decreases being K26A >> W25A > K24A = K28A. Also, substitutions made in the 3(10)-helix (residues 3-7), a region located close to the beta-turn, produced equivalent effects (K3A > K6A). Thus, it is deduced that residues in the distorted beta-turn and neighboring 3(10)-helix of DTX(K) are critical for its interaction with neuronal K+ channels.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
24
pubmed:volume
36
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
7690-6
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Site-directed mutagenesis of dendrotoxin K reveals amino acids critical for its interaction with neuronal K+ channels.
pubmed:affiliation
Department of Immunology and Molecular Biology, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702-5011, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't