5t8a
Recombinant cytotoxin-I from the venom of cobra N. oxiana
Structural highlights
Function3SA1_NAJOX This three-finger cytotoxin is a basic protein that interacts and penetrates into the cell membrane, with the tips of all the three loops. Cytotoxins which have a 'Pro-30' (P-type) interacts with membrane stronger that those which have a Ser-28 (S-type). CTI interacts with membrane weaker than CTII. Publication Abstract from PubMedToday, recombinant proteins are quite widely used in biomedical and biotechnological applications. At the same time, the question about their full equivalence to the native analogues remains unanswered. To gain additional insight into this problem, intimate atomistic details of a relatively simple protein, small and structurally rigid recombinant cardiotoxin I (CTI) from cobra Naja oxiana venom, were characterized using nuclear magnetic resonance (NMR) spectroscopy and atomistic molecular dynamics (MD) simulations in water. Compared to the natural protein, it contains an additional Met residue at the N-terminus. In this work, the NMR-derived spatial structure of uniformly 13C- and 15N-labeled CTI and its dynamic behavior were investigated and subjected to comparative analysis with the corresponding data for the native toxin. The differences were found in dihedral angles of only a single residue, adjacent to the N-terminal methionine. Microsecond-long MD traces of the toxins reveal an increased flexibility in the residues spatially close to the N-Met. As the detected structural and dynamic changes of the two CTI models do not result in substantial differences in their cytotoxicities, we assume that the recombinant protein can be used for many purposes as a reasonable surrogate of the native one. In addition, we discuss general features of the spatial organization of cytotoxins, implied by the results of the current combined NMR and MD study. Structural and Dynamic "Portraits" of Recombinant and Native Cytotoxin I from Naja oxiana: How Close Are They?,Dubovskii PV, Dubinnyi MA, Konshina AG, Kazakova ED, Sorokoumova GM, Ilyasova TM, Shulepko MA, Chertkova RV, Lyukmanova EN, Dolgikh DA, Arseniev AS, Efremov RG Biochemistry. 2017 Aug 29;56(34):4468-4477. doi: 10.1021/acs.biochem.7b00453., Epub 2017 Aug 14. PMID:28749688[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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