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Structure paper

タイトル	Target preference of Type III-A CRISPR-Cas complexes at the transcription bubble.
ジャーナル・号・ページ	Nat Commun, Vol. 10, Issue 1, Page 3001, Year 2019
掲載日	2019年7月5日
著者	Tina Y Liu / Jun-Jie Liu / Abhishek J Aditham / Eva Nogales / Jennifer A Doudna /
PubMed 要旨	Type III-A CRISPR-Cas systems are prokaryotic RNA-guided adaptive immune systems that use a protein-RNA complex, Csm, for transcription-dependent immunity against foreign DNA. Csm can cleave RNA and ...Type III-A CRISPR-Cas systems are prokaryotic RNA-guided adaptive immune systems that use a protein-RNA complex, Csm, for transcription-dependent immunity against foreign DNA. Csm can cleave RNA and single-stranded DNA (ssDNA), but whether it targets one or both nucleic acids during transcription elongation is unknown. Here, we show that binding of a Thermus thermophilus (T. thermophilus) Csm (TthCsm) to a nascent transcript in a transcription elongation complex (TEC) promotes tethering but not direct contact of TthCsm with RNA polymerase (RNAP). Biochemical experiments show that both TthCsm and Staphylococcus epidermidis (S. epidermidis) Csm (SepCsm) cleave RNA transcripts, but not ssDNA, at the transcription bubble. Taken together, these results suggest that Type III systems primarily target transcripts, instead of unwound ssDNA in TECs, for immunity against double-stranded DNA (dsDNA) phages and plasmids. This reveals similarities between Csm and eukaryotic RNA interference, which also uses RNA-guided RNA targeting to silence actively transcribed genes.
リンク	Nat Commun / PubMed:31278272 / PubMed Central
手法	EM (単粒子)
解像度	3.8 - 17.0 Å
構造データ	0454 6o1o EMDB-0454, PDB-6o1o: Cryo-EM structure of the T. thermophilus Csm complex bound to target ssRNA 手法: EM (単粒子) / 解像度: 3.8 Å EMDB-0455: Negative stain EM structure of T. thermophilus Csm with a transcription elongation complex 手法: EM (単粒子) / 解像度: 17.0 Å
由来	thermus thermophilus (サーマス・サーモフィルス)
キーワード	RNA BINDING PROTEIN/RNA / Csm / RNA substrate / RNA BINDING PROTEIN (RNA結合タンパク質) / RNA BINDING PROTEIN-RNA complex