Nuclear export inhibition through covalent conjugation and hydrolysis of Leptomycin B by CRM1.

Sun, Qingxiang; Carrasco, Yazmin P; Hu, Youcai; Guo, Xiaofeng; Mirzaei, Hamid; Macmillan, John; Chook, Yuh Min · Proc Natl Acad Sci U S A · 2013

basic_science · Level V

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Abstract

The polyketide natural product Leptomycin B inhibits nuclear export mediated by the karyopherin protein chromosomal region maintenance 1 (CRM1). Here, we present 1.8- to 2.0-Å-resolution crystal structures of CRM1 bound to Leptomycin B and related inhibitors Anguinomycin A and Ratjadone A. Structural and complementary chemical analyses reveal an unexpected mechanism of inhibition involving covalent conjugation and CRM1-mediated hydrolysis of the natural products' lactone rings. Furthermore, mutagenesis reveals the mechanism of hydrolysis by CRM1. The nuclear export signal (NES)-binding groove of CRM1 is able to drive a chemical reaction in addition to binding protein cargoes for transport through the nuclear pore complex.

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