The Mtr4 ratchet helix and arch domain both function to promote RNA unwinding.
The Mtr4 ratchet helix and arch domain both function to promote RNA unwinding.
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DOI：
10.1093/nar/gku1208
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发表时间：
2014-12-16
影响因子：
14.9
通讯作者：
Johnson SJ
中科院分区：
文献类型：
--
作者：
Taylor LL;Jackson RN;Rexhepaj M;King AK;Lott LK;van Hoof A;Johnson SJ
Mtr4是一种保守的ski2样RNA解旋酶，也是TRAMP复合体的一个亚基，在核RNA监视和加工途径中激活外泌体介导的3 ‘ -5 ’转换。Mtr4结构的突出特征包括一个四结构域环状解旋酶核心和一个跨越核心的大拱形结构域。当RNA底物通过解旋酶时，“棘轮螺旋”被定位为与它们相互作用。然而，棘轮螺旋在Mtr4活性中的作用尚不清楚。在这里，我们发现与相关的解旋酶相比，ski2样RNA解旋酶沿着棘轮螺旋的严格保守性尤其广泛。沿着棘轮螺旋的残基突变会改变Mtr4和TRAMP的体外活性，并导致体内生长缓慢的表型。我们还发现棘轮螺旋上的残基影响Mtr4对聚腺苷化底物的亲和力。先前的研究表明，拱形结构域的缺失对Mtr4解绕活性的影响很小。我们现在表明，将弓形缺失与棘轮螺旋突变结合可以消除解旋酶活性，并产生致命的体内表型。这些研究表明棘轮螺旋调节解旋酶活性，并表明拱形结构域在解绕底物中起着以前未被认识到的作用。
Mtr4 is a conserved Ski2-like RNA helicase and a subunit of the TRAMP complex that activates exosome-mediated 3′-5′ turnover in nuclear RNA surveillance and processing pathways. Prominent features of the Mtr4 structure include a four-domain ring-like helicase core and a large arch domain that spans the core. The ‘ratchet helix’ is positioned to interact with RNA substrates as they move through the helicase. However, the contribution of the ratchet helix in Mtr4 activity is poorly understood. Here we show that strict conservation along the ratchet helix is particularly extensive for Ski2-like RNA helicases compared to related helicases. Mutation of residues along the ratchet helix alters in vitro activity in Mtr4 and TRAMP and causes slow growth phenotypes in vivo. We also identify a residue on the ratchet helix that influences Mtr4 affinity for polyadenylated substrates. Previous work indicated that deletion of the arch domain has minimal effect on Mtr4 unwinding activity. We now show that combining the arch deletion with ratchet helix mutations abolishes helicase activity and produces a lethal in vivo phenotype. These studies demonstrate that the ratchet helix modulates helicase activity and suggest that the arch domain plays a previously unrecognized role in unwinding substrates.
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影响因子：
14.9
作者：
Klauer AA;van Hoof A
通讯作者：
van Hoof A
影响因子：
7.7
作者：
He, Yangzi;Andersen, Gregers R.;Nielsen, Klaus H.
通讯作者：
Nielsen, Klaus H.
影响因子：
10.5
作者：
Allmang, C;Petfalski, E;Mitchell, P
通讯作者：
Mitchell, P
影响因子：
16.8
作者：
Buettner, Katharina;Nehring, Sebastian;Hopfner, Karl-Peter
通讯作者：
Hopfner, Karl-Peter
DOI：
10.1107/s0907444909052925
发表时间：
2010-02
期刊：
Acta crystallographica. Section D, Biological crystallography
影响因子：
--
作者：
Adams PD;Afonine PV;Bunkóczi G;Chen VB;Davis IW;Echols N;Headd JJ;Hung LW;Kapral GJ;Grosse-Kunstleve RW;McCoy AJ;Moriarty NW;Oeffner R;Read RJ;Richardson DC;Richardson JS;Terwilliger TC;Zwart PH
通讯作者：
Zwart PH