Molecular architecture of zinc chelating small molecules that inhibit spliceosome assembly at an early stage.

Vishal Patil, Josh C Canzoneri, Timur R Samatov, Reinhard Lührmann, Adegboyega K Oyelere

RNA (New York, N.Y.) 2012 Sep

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The removal of intervening sequences (introns) from a primary RNA transcript is catalyzed by the spliceosome, a large ribonucleoprotein complex. At the start of each splicing cycle, the spliceosome assembles anew in a sequentially ordered manner on the pre-mRNA intron to be removed. We describe here the identification of a series of naphthalen-2-yl hydroxamate compounds that inhibit pre-mRNA splicing in vitro with mid- to high-micromolar values of IC(50). These hydroxamates stall spliceosome assembly at the A complex stage. A structure-activity analysis of lead compounds revealed three pharmacophores that are essential for splicing inhibition. Specifically, a hydroxamate as a zinc-binding group and a 6-methoxynaphthalene cap group are both critical, and a linker chain comprising eight to nine methylene groups is also important, for the specific binding to the docking site of a target protein molecule and precise positioning of the zinc binding group. As we found no correlation between the inhibition patterns of known histone deacetylases on the one hand and pre-mRNA splicing on the other, we conclude that these compounds may function through the inhibition of the activities of other, at present, unknown spliceosome-associated zinc metalloprotein(s).

Citation

Vishal Patil, Josh C Canzoneri, Timur R Samatov, Reinhard Lührmann, Adegboyega K Oyelere. Molecular architecture of zinc chelating small molecules that inhibit spliceosome assembly at an early stage. RNA (New York, N.Y.). 2012 Sep;18(9):1605-11