Spliceosome disassembly catalyzed by Prp43 and its associated components Ntr1 and Ntr2.

Rong-Tzong Tsai, Ru-Huei Fu, Fu-Lung Yeh, Chi-Kang Tseng, Yu-Chieh Lin, Yu-Hsin Huang, Soo-Chen Cheng

Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China.

Genes & development 2005 Dec 15

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Two novel yeast splicing factors required for spliceosome disassembly have been identified. Ntr1 and Ntr2 (NineTeen complex-Related proteins) were identified for their weak association with components of the Prp19-associated complex. Unlike other Prp19-associated components, these two proteins were primarily associated with the intron-containing spliceosome during the splicing reaction. Extracts depleted of Ntr1 or Ntr2 exhibited full splicing activity, but accumulated large amounts of lariat-intron in the spliceosome after splicing, indicating that the normal function of the Prp19-associated complex in spliceosome activation was not affected, but spliceosome disassembly was hindered. Immunoprecipitation analysis revealed that Ntr1 and Ntr2 formed a stable complex with DExD/H-box RNA helicase Prp43 in the splicing extract. Ntr1 interacted with Prp43 through the N-terminal G-patch domain, with Ntr2 through a middle region, and with itself through the carboxyl half of the protein. The affinity-purified Ntr1-Ntr2-Prp43 complex could catalyze disassembly of the spliceosome in an ATP-dependent manner, separating U2, U5, U6, NTC (NineTeen Complex), and lariat-intron. This is the first demonstration of physical disassembly of the spliceosome, catalyzed by a complex containing a DExD/H-box RNA helicase and two accessory factors, which might function in targeting the helicase to the correct substrate.

Citation

Rong-Tzong Tsai, Ru-Huei Fu, Fu-Lung Yeh, Chi-Kang Tseng, Yu-Chieh Lin, Yu-Hsin Huang, Soo-Chen Cheng. Spliceosome disassembly catalyzed by Prp43 and its associated components Ntr1 and Ntr2. Genes & development. 2005 Dec 15;19(24):2991-3003