E. coli elongation factor Tu bound to a GTP analogue displays an open conformation equivalent to the GDP-bound form.
E. coli elongation factor Tu bound to a GTP analogue displays an open conformation equivalent to the GDP-bound form.
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DOI：
10.1093/nar/gky697
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发表时间：
2018-09-19
影响因子：
14.9
通讯作者：
Knudsen CR
中科院分区：
文献类型：
--
作者：
Johansen JS;Kavaliauskas D;Pfeil SH;Blaise M;Cooperman BS;Goldman YE;Thirup SS;Knudsen CR
根据传统观点，GTP酶作为分子开关，分别在与GTP和GDP结合的不同“开启”和“关闭”构象之间循环。翻译延伸因子EF - Tu是原核生物蛋白质合成所必需的一种GTP酶。在其与GTP结合的形式下，EF - Tu作为三元复合物将氨酰化的tRNAs运送到核糖体。据认为，由于Pi释放后发生剧烈的构象变化，GTP水解导致EF - Tu从氨酰 - tRNA和核糖体上释放。在此，已经确定了大肠杆菌EF - Tu与一种不可水解的GTP类似物（GDPNP）形成的复合物的晶体结构。值得注意的是，EF - Tu·GDPNP的整体构象呈现出经典的、开放的与GDP结合的构象。这与一种新出现的观点相符，即结合的鸟嘌呤核苷酸的种类并没有将GTP酶“锁定”在一个固定的构象中。利用单分子方法，通过荧光共振能量转移在溶液中探测了EF - Tu的各种配体结合形式的构象动力学。结果表明，在溶液中游离的EF - Tu可能比先前X射线晶体学研究中已知的结构明确的GTP和GDP形式具有更广泛的构象。只有当作为三元复合物与mRNA编程的核糖体结合时，才会观察到众所周知的、闭合的与GTP结合的构象。
According to the traditional view, GTPases act as molecular switches, which cycle between distinct ‘on’ and ‘off’ conformations bound to GTP and GDP, respectively. Translation elongation factor EF-Tu is a GTPase essential for prokaryotic protein synthesis. In its GTP-bound form, EF-Tu delivers aminoacylated tRNAs to the ribosome as a ternary complex. GTP hydrolysis is thought to cause the release of EF-Tu from aminoacyl-tRNA and the ribosome due to a dramatic conformational change following Pi release. Here, the crystal structure of Escherichia coli EF-Tu in complex with a non-hydrolysable GTP analogue (GDPNP) has been determined. Remarkably, the overall conformation of EF-Tu·GDPNP displays the classical, open GDP-bound conformation. This is in accordance with an emerging view that the identity of the bound guanine nucleotide is not ‘locking’ the GTPase in a fixed conformation. Using a single-molecule approach, the conformational dynamics of various ligand-bound forms of EF-Tu were probed in solution by fluorescence resonance energy transfer. The results suggest that EF-Tu, free in solution, may sample a wider set of conformations than the structurally well-defined GTP- and GDP-forms known from previous X-ray crystallographic studies. Only upon binding, as a ternary complex, to the mRNA-programmed ribosome, is the well-known, closed GTP-bound conformation, observed.
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影响因子：
64.5
作者：
Lin J;Gagnon MG;Bulkley D;Steitz TA
通讯作者：
Steitz TA
影响因子：
14.9
作者：
Kavaliauskas D;Chen C;Liu W;Cooperman BS;Goldman YE;Knudsen CR
通讯作者：
Knudsen CR
影响因子：
5.7
作者：
KJELDGAARD, M;NISSEN, P;NYBORG, J
通讯作者：
NYBORG, J
DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
DOI：
10.1107/s0907444906004021
发表时间：
2006-04-01
影响因子：
2.2
作者：
Heffron, SE;Moeller, R;Jurnak, F
通讯作者：
Jurnak, F