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Binding of kinetin in the active site of mistletoe lectin I
Structural highlights
FunctionML1_VISAL The A chain is responsible for inhibiting protein synthesis through the catalytic inactivation of 60S ribosomal subunits by removing adenine from position 4,324 of 28S rRNA. The B chain binds to cell receptors and probably facilitates the entry into the cell of the A chain; B chains are also responsible for cell agglutination (lectin activity). Inhibits growth of the human tumor cell line Molt4.[1] [2] [3] Publication Abstract from PubMedThe crystal structure of the ribosome inhibiting protein Mistletoe Lectin I (ML-I) derived from the European mistletoe, Viscum album, in complex with kinetin has been refined at 2.7A resolution. Suitably large crystals of ML-I were obtained applying the counter diffusion method using the Gel Tube R Crystallization Kit (GT-R) on board the Russian Service Module on the international space station ISS within the GCF mission No. 6, arranged by the Japanese aerospace exploration agency (JAXA). Hexagonal bi-pyramidal crystals were grown during three months under microgravity. Before data collection the crystals were soaked in a saturated solution of kinetin and diffraction data to 2.7A were collected using synchrotron radiation and cryogenic techniques. The atomic model was refined and revealed a single kinetin molecule in the ribosome inactivation site of ML-I. The complex demonstrates the feasibility of mistletoe to bind plant hormones out of the host regulation system as part of a self protection mechanism. Binding of the plant hormone kinetin in the active site of Mistletoe Lectin I from Viscum album.,Malecki PH, Rypniewski W, Szymanski M, Barciszewski J, Meyer A Biochim Biophys Acta. 2012 Feb;1824(2):334-8. doi: 10.1016/j.bbapap.2011.10.013. , Epub 2011 Oct 28. PMID:22064121[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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