TAILIEUCHUNG - Báo cáo khoa học: Conformation and mode of membrane interaction in cyclotides

Cyclotides are a family of bioactive plant peptides that are characterized by a circular protein backbone and three conserved tightly packed disulfide bonds. The antimicrobial and hemolytic properties of cyclotides, along with the relative hydrophobicity of the peptides, point to the biological mem-brane as a target for cyclotides. | iFEBS Journal Conformation and mode of membrane interaction in cyclotides Spatial structure of kalata B1 bound to a dodecylphosphocholine micelle Zakhar O. Shenkarev1 Kirill D. Nadezhdin1 Vladimir A. Sobol1 Alexander G. Sobol1 Lars Skjeldal2 and Alexander S. Arseniev1 1 Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences Moscow Russia 2 Norwegian University of Life Sciences IKBM Aas Norway Keywords cystine knot divalent cation-binding site natural abundance 13C-NMR spectroscopy knottin quantitative J-correlation Correspondence A. S. Arseniev Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry Russian Academy of Sciences ul. Miklukho-Maklaya 16 10 117871 Moscow Russia Fax 7 095 3355033 Tel 7 095 3305929 E-mail aars@ Received 20 February 2006 revised 8 April 2006 accepted 12 April 2006 doi Cyclotides are a family of bioactive plant peptides that are characterized by a circular protein backbone and three conserved tightly packed disulfide bonds. The antimicrobial and hemolytic properties of cyclotides along with the relative hydrophobicity of the peptides point to the biological membrane as a target for cyclotides. To assess the membrane-induced conformation and orientation of cyclotides the interaction of the Mobius cyclotide kalata B1 from the African perennial plant Oldenlandia affinis with dodecylphosphocholine micelles was studied using NMR spectroscopy. Under conditions where the cyclotide formed a well-defined complex with micelles the spatial structure of kalata B1 was calculated from NOE and J couplings data and the model for the peptide-micelle complex was built using 5- and 16-doxylstearate relaxation probes. The binding of divalent cations to the peptide-micelle complex was quantified by Mn2 titration. The results show that the peptide binds to the micelle surface with relatively high affinity via two hydrophobic loops loop 5 Trp19-Val21 and loop6 Leu27-Val29 . The charged residues

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