Glutamine Hydrolysis by Imidazole Glycerol Phosphate Synthase Displays Temperature Dependent Allosteric Activation.
Glutamine Hydrolysis by Imidazole Glycerol Phosphate Synthase Displays Temperature Dependent Allosteric Activation.
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DOI：
10.3389/fmolb.2018.00004
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发表时间：
2018
影响因子：
5
通讯作者：
Loria JP
中科院分区：
文献类型：
--
作者：
Lisi GP;Currier AA;Loria JP
咪唑甘油磷酸合成酶(IGPS)是研究酶的长程变构调节的模型。变构效应配体N‘-[5’-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamide-ribonucleotide(PrFAR)的结合刺激IGP的毫秒(Ms)时间尺度运动，从而增强其催化功能。我们研究了温度对这些临界构象运动的影响以及高温嗜热菌的IGPS的催化机制，以期了解依赖于温度的变构。酶动力学和核磁共振动力学测量表明，apo和PRFAR激活的IGP对温度变化的反应不同。在303、323和343K(30、50和70°C)下进行的多量子Carr-Purcell-Meiom-Gill(CPMG)弛豫色散实验表明，随着样品温度的升高，apo IGPS的毫秒灵活性比PrFAR结合酶的增强程度更高。我们发现，在343K时，apo酶的柔韧性与其PRFAR激活状态的柔韧性几乎相同，而在室温下，这两种形式的酶的构象运动有很大的不同。Arrhenius对这些柔性位的分析显示了不同范围的活化能，这些活化能与计算方法确定的变构群落松散相关，并反映了动力学的局部变化，这可能有助于活性构象的构象采样。此外，动力学分析表明，在343K时，PRFAR的变构激活减少到65倍，而在303K时是4200倍，这反映了PRFAR相对于未激活的酶对ms运动的抑制作用。这些研究表明，在毛霉菌的生长温度下，PFRAR是一种比室温下更弱的变构激活剂，说明IGPS的变构机理与温度有关。
The enzyme imidazole glycerol phosphate synthase (IGPS) is a model for studies of long-range allosteric regulation in enzymes. Binding of the allosteric effector ligand N'-[5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamide-ribonucleotide (PRFAR) stimulates millisecond (ms) timescale motions in IGPS that enhance its catalytic function. We studied the effect of temperature on these critical conformational motions and the catalytic mechanism of IGPS from the hyperthermophile Thermatoga maritima in an effort to understand temperature-dependent allostery. Enzyme kinetic and NMR dynamics measurements show that apo and PRFAR-activated IGPS respond differently to changes in temperature. Multiple-quantum Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion experiments performed at 303, 323, and 343 K (30, 50, and 70°C) reveal that millisecond flexibility is enhanced to a higher degree in apo IGPS than in the PRFAR-bound enzyme as the sample temperature is raised. We find that the flexibility of the apo enzyme is nearly identical to that of its PRFAR activated state at 343 K, whereas conformational motions are considerably different between these two forms of the enzyme at room temperature. Arrhenius analyses of these flexible sites show a varied range of activation energies that loosely correlate to allosteric communities identified by computational methods and reflect local changes in dynamics that may facilitate conformational sampling of the active conformation. In addition, kinetic assays indicate that allosteric activation by PRFAR decreases to 65-fold at 343 K, compared to 4,200-fold at 303 K, which mirrors the decreased effect of PRFAR on ms motions relative to the unactivated enzyme. These studies indicate that at the growth temperature of T. maritima, PFRAR is a weaker allosteric activator than it is at room temperature and illustrate that the allosteric mechanism of IGPS is temperature dependent.
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影响因子：
2.7
作者：
d'Auvergne EJ;Gooley PR
通讯作者：
Gooley PR
影响因子：
2.7
作者：
d'Auvergne EJ;Gooley PR
通讯作者：
Gooley PR
DOI：
10.1002/prot.340220410
发表时间：
1995-08-01
期刊：
PROTEINS-STRUCTURE FUNCTION AND GENETICS
影响因子：
--
作者：
GOMEZ, J;HILSER, VJ;FREIRE, E
通讯作者：
FREIRE, E
影响因子：
4.3
作者：
Daily MD;Phillips GN Jr;Cui Q
通讯作者：
Cui Q
影响因子：
2.7
作者：
DELAGLIO, F;GRZESIEK, S;BAX, A
通讯作者：
BAX, A