title: Cytotoxicity of recombinant tamapin and related toxin-like peptides on model cell lines.
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.
authors.affiliation: Instituto de Química, Universidad Nacional Autónoma de México , Ciudad Universitaria, Circuito Exterior s/n, México, D.F. 04510, México.
authors.forename: Belén
authors.initials: B
authors.lastname: Ramírez-Cordero
authors.forename: Yanis
authors.initials: Y
authors.lastname: Toledano
authors.forename: Patricia
authors.initials: P
authors.lastname: Cano-Sánchez
authors.forename: Rogelio
authors.initials: R
authors.lastname: Hernández-López
authors.forename: David
authors.initials: D
authors.lastname: Flores-Solis
authors.forename: Alma L
authors.initials: AL
authors.lastname: Saucedo-Yáñez
authors.forename: Isabel
authors.initials: I
authors.lastname: Chávez-Uribe
authors.forename: Luis G
authors.initials: LG
authors.lastname: Brieba
authors.forename: Federico
authors.initials: F
authors.lastname: del Río-Portilla
mesh_terms: D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D019169:Jurkat Cells; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects; D008958:Models, Molecular; D009498:Neurotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D012604:Scorpion Venoms / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured
chemical_list: D009498:Neurotoxins; D010455:Peptides; D011994:Recombinant Proteins; D012604:Scorpion Venoms; C000597457:tamapin peptide, Mesobuthus tamulus