2MEL

NMR solution structure of the GS-TAMAPIN MUTATION R7A

Summary for 2MEL

• Entry DOI: 10.2210/pdb2mel/pdb
• Related: 2ME7 2MEN 2MEO
• NMR Information: BMRB: 19524
• Descriptor: Potassium channel toxin alpha-KTx 5.4 (1 entity in total)
• Functional Keywords: scorpion toxin, tamapin, alpha ktx5.4 mutant r7a, toxin
• Biological source: Mesobuthus tamulus (eastern Indian scorpion)
• Cellular location: Secreted: P59869
• Total number of polymer chains: 1
• Total formula weight: 3528.20

Authors

del Rio-Portilla, F.,Ramirez-Cordero, B. (deposition date: 2013-09-24, release date: 2014-05-28, Last modification date: 2024-10-30)

Primary citation

Ramirez-Cordero, B.,Toledano, Y.,Cano-Sanchez, P.,Hernandez-Lopez, R.,Flores-Solis, D.,Saucedo-Yanez, A.L.,Chavez-Uribe, I.,Brieba, L.G.,Del Rio-Portilla, F.
Cytotoxicity of recombinant tamapin and related toxin-like peptides on model cell lines.
Chem.Res.Toxicol., 27:960-967, 2014

PubMed Abstract: The scorpion toxin tamapin displays the most potent and selective blockage against KCa2.2 channels known to date. In this work, we report the biosynthesis, three-dimensional structure, and cytotoxicity on cancer cell lines (Jurkat E6-1 and human mammary breast cancer MDA-MB-231) of recombinant tamapin and five related peptides bearing mutations on residues (R6A,R7A, R13A, R6A-R7A, and GS-tamapin) that were previously suggested to be important for tamapin's activity. The indicated cell lines were used as they constitutively express KCa2.2 channels. The studied toxin-like peptides displayed lethal responses on Jurkat T cells and breast cancer cells; their effect is dose- and time-dependent with IC50 values in the nanomolar range. The order of potency is r-tamapin>GS-tamapin>R6A>R13A>R6A-R7A>R7A for Jurkat T cells and r-tamapin>R7A for MDA-MB-231 breast cancer cells. Our structural determination by NMR demonstrated that r-tamapin preserves the folding of the αKTx5 subfamily and that neither single nor double alanine mutations affect the three-dimensional structure of the wild-type peptide. In contrast, our activity assays show that changes in cytotoxicity are related to the chemical nature of certain residues. Our results suggest that the toxic activity of r-tamapin on Jurkat and breast cancer cells could be mediated by the interaction of charged residues in tamapin with KCa2.2 channels via the apoptotic cell death pathway.

PubMed: 24821061
DOI: 10.1021/tx4004193

Experimental method

SOLUTION NMR