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-Structure paper
タイトル | Structures and single-molecule analysis of bacterial motor nuclease AdnAB illuminate the mechanism of DNA double-strand break resection. |
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ジャーナル・号・ページ | Proc Natl Acad Sci U S A, Vol. 116, Issue 49, Page 24507-24516, Year 2019 |
掲載日 | 2019年12月3日 |
著者 | Ning Jia / Mihaela C Unciuleac / Chaoyou Xue / Eric C Greene / Dinshaw J Patel / Stewart Shuman / |
PubMed 要旨 | Mycobacterial AdnAB is a heterodimeric helicase-nuclease that initiates homologous recombination by resecting DNA double-strand breaks (DSBs). The AdnA and AdnB subunits are each composed of an N- ...Mycobacterial AdnAB is a heterodimeric helicase-nuclease that initiates homologous recombination by resecting DNA double-strand breaks (DSBs). The AdnA and AdnB subunits are each composed of an N-terminal motor domain and a C-terminal nuclease domain. Here we report cryoelectron microscopy (cryo-EM) structures of AdnAB in three functional states: in the absence of DNA and in complex with forked duplex DNAs before and after cleavage of the 5' single-strand DNA (ssDNA) tail by the AdnA nuclease. The structures reveal the path of the 5' ssDNA through the AdnA nuclease domain and the mechanism of 5' strand cleavage; the path of the 3' tracking strand through the AdnB motor and the DNA contacts that couple ATP hydrolysis to mechanical work; the position of the AdnA iron-sulfur cluster subdomain at the Y junction and its likely role in maintaining the split trajectories of the unwound 5' and 3' strands. Single-molecule DNA curtain analysis of DSB resection reveals that AdnAB is highly processive but prone to spontaneous pausing at random sites on duplex DNA. A striking property of AdnAB is that the velocity of DSB resection slows after the enzyme experiences a spontaneous pause. Our results highlight shared as well as distinctive properties of AdnAB vis-à-vis the RecBCD and AddAB clades of bacterial DSB-resecting motor nucleases. |
リンク | Proc Natl Acad Sci U S A / PubMed:31740608 / PubMed Central |
手法 | EM (単粒子) |
解像度 | 3.5 Å |
構造データ | EMDB-20440, PDB-6ppj: EMDB-20446, PDB-6ppr: EMDB-20447, PDB-6ppu: |
化合物 | ChemComp-SF4: ChemComp-ANP: ChemComp-MG: |
由来 |
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キーワード | DNA BINDING PROTEIN / DNA BINDING PROTEIN/DNA / DNA / DNA BINDING PROTEIN-DNA complex |