title: The Kunitz-Type Protein ShPI-1 Inhibits Serine Proteases and Voltage-Gated Potassium Channels.
abstract: The bovine pancreatic trypsin inhibitor (BPTI)-Kunitz-type protein ShPI-1 (UniProt: P31713) is the major protease inhibitor from the sea anemone Stichodactyla helianthus. This molecule is used in biotechnology and has biomedical potential related to its anti-parasitic effect. A pseudo wild-type variant, rShPI-1A, with additional residues at the N- and C-terminal, has a similar three-dimensional structure and comparable trypsin inhibition strength. Further insights into the structure-function relationship of rShPI-1A are required in order to obtain a better understanding of the mechanism of action of this sea anemone peptide. Using enzyme kinetics, we now investigated its activity against other serine proteases. Considering previous reports of bifunctional Kunitz-type proteins from anemones, we also studied the effect of rShPI-1A on voltage-gated potassium (Kv) channels. rShPI-1A binds Kv1.1, Kv1.2, and Kv1.6 channels with IC50 values in the nM range. Hence, ShPI-1 is the first member of the sea anemone type 2 potassium channel toxins family with tight-binding potency against several proteases and different Kv1 channels. In depth sequence analysis and structural comparison of ShPI-1 with similar protease inhibitors and Kv channel toxins showed apparent non-sequence conservation for known key residues. However, we detected two subtle patterns of coordinated amino acid substitutions flanking the conserved cysteine residues at the N- and C-terminal ends.
authors.affiliation: Centro de Estudio de Proteínas, Facultad de Biología, Universidad de la Habana, Calle 25 No. 455, 10400 La Habana, Cuba. rossana.gf@gmail.com.
authors.forename: Rossana
authors.initials: R
authors.lastname: García-Fernández
authors.affiliation: Laboratory of Toxicology and Pharmacology, KU Leuven, Campus Gasthuisberg O&amp;N2, Herestraat 49, P.O. Box 922, B-3000 Leuven, Belgium. steve.peigneur@pharm.kuleuven.be.
authors.forename: Steve
authors.initials: S
authors.lastname: Peigneur
authors.affiliation: Structural Biology and Biocomputing Programme, Spanish National Cancer Research Centre (CNIO), C/Melchor Fernández Almagro 3, Madrid E-28029, Spain. tpons@cnio.es.
authors.forename: Tirso
authors.initials: T
authors.lastname: Pons
authors.affiliation: Centro de Estudio de Proteínas, Facultad de Biología, Universidad de la Habana, Calle 25 No. 455, 10400 La Habana, Cuba. calvarez@fbio.uh.cu.
authors.forename: Carlos
authors.initials: C
authors.lastname: Alvarez
authors.affiliation: Centro de Estudio de Proteínas, Facultad de Biología, Universidad de la Habana, Calle 25 No. 455, 10400 La Habana, Cuba. libelulalid@gmail.com.
authors.forename: Lidice
authors.initials: L
authors.lastname: González
authors.affiliation: Centro de Estudio de Proteínas, Facultad de Biología, Universidad de la Habana, Calle 25 No. 455, 10400 La Habana, Cuba. mchavez@fbio.uh.cu.
authors.forename: María A
authors.initials: MA
authors.lastname: Chávez
authors.affiliation: Laboratory of Toxicology and Pharmacology, KU Leuven, Campus Gasthuisberg O&amp;N2, Herestraat 49, P.O. Box 922, B-3000 Leuven, Belgium. jan.tytgat@pharm.kuleuven.be.
authors.forename: Jan
authors.initials: J
authors.lastname: Tytgat
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D007611:Aprotinin / Q000737:chemistry / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D024642:Potassium Channels, Voltage-Gated / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000494:pharmacology; D057057:Serine Proteases / Q000502:physiology; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology*; D014982:Xenopus laevis
chemical_list: D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated; D011994:Recombinant Proteins; D015842:Serine Proteinase Inhibitors; D007611:Aprotinin; D057057:Serine Proteases
keywords: Kunitz-type protein; Kv channel inhibitor; protease inhibitor; sea anemone; toxin