Architecture of the yeast Rrp44-exosome complex suggests routes of RNA recruitment for 3 '; end processing

作者：Wang Hong Wei^*; Wang Jianjun; Ding Fang; Callahan Kevin; Bratkowski Matthew A; Butler J Scott; Nogales Eva; Ke Ailong

来源：Proceedings of the National Academy of Sciences, 2007, 104(43): 16844-16849.

DOI：10.1073/pnas.0705526104

• electron microscopy
• single-particle reconstruction
• exoribonuclease

The eukaryotic core exosome (CE) is a conserved nine-subunit protein complex important for 3'; end trimming and degradation of RNA. In yeast, the Rrp44 protein constitutively associates with the CE and provides the sole source of processive 3';-to-5'; exoribonuclease activity. Here we present EM reconstructions of the core and Rrp44-bound exosome complexes. The two-lobed Rrp44 protein binds to the RNase PH domain side of the exosome and buttresses the bottom of the exosome-processing chamber. The Rrp44 C-terminal body part containing an RNase II-type active site is anchored to the exosome through a conserved set of interactions mainly to the Rrp45 and Rrp43 subunit, whereas the Rrp44 N-terminal head part is anchored to the Rrp41 subunit and may function as a roadblock to restrict access of RNA to the active site in the body region. The Rrp44-exosorne (RE) architecture suggests an active site sequestration mechanism for strict control of 3'; exoribonuclease activity in the RE complex.

• 出版日期2007-10-23