Cloning and Expression of Catalytic Subunit of MLIII, the Ribosome-Inactivating Protein from Viscum album

A. G. Tonevitsky^1*, I. I. Agapov¹, I. B. Pevzner¹, N. V. Malyuchenko¹, M. M. Moisenovich¹, U. Pfueller², and M. P. Kirpichnikov¹

¹Faculty of Biology, Lomonosov Moscow State University, Moscow 119899, Russia; fax: (7-095) 196-0522; E-mail: tonevits@genetika.ru

²Institute of Phytochemistry, University of Witten/Herdecke, Stockumer Str. 10, D-58448, Witten, Germany; E-mail: uwep@uni-wh.de

^* To whom correspondence should be addressed.

Received July 28, 2003; Revision received October 15, 2003

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We have cloned the gene encoding a precursor of mistletoe (Viscum album) toxin MLIII. Analyses of nucleotide and deduced amino acid sequences of this gene revealed significant differences between MLI and MLIII preprotoxin genes. Immunochemical properties of recombinant A-subunit expressed in Escherichia coli and renatured were investigated using a panel of monoclonal antibodies raised against three mistletoe toxins (MLI, MLII, and MLIII). Ribosome-inactivating activity of recombinant MLIII A-subunit was detected in cell-free lysate of rabbit reticulocytes.

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KEY WORDS: mistletoe toxin, recombinant MLIII A-subunit, monoclonal antibodies

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