Protein-Ribofuranosyl Interactions Activate Orotidine 5'-Monophosphate Decarboxylase for Catalysis.
Protein-Ribofuranosyl Interactions Activate Orotidine 5'-Monophosphate Decarboxylase for Catalysis.
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DOI：
10.1021/acs.biochem.1c00589
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发表时间：
2021-11-16
期刊：
影响因子：
2.9
通讯作者：
Richard JP
中科院分区：
文献类型：
--
作者：
Cristobal JR;Brandão TAS;Reyes AC;Richard JP
在侧重于 OMPDC 与 OMP 核糖基羟基之间相互作用的实验中，研究了全局底物驱动的酶构象变化在乳清苷 5'-单磷酸脱羧酶 (OMPDC) 催化的乳清苷 5'-单磷酸 (OMP) 脱羧反应中的作用。 OMPDC 的 D37 和 T100' 侧链分别与酶结合的 OMP 的 C-3' 和 C-2' 羟基相互作用。 D37G 和 T100’A 取代导致磷酸二价阴离子截短底物 1-(β-D-赤呋喃糖基)乳清酸 (EO) 脱羧催化的活化势垒 ΔG‡ 增加 1.4 kcal/mol，但 OMP 脱羧和亚磷酸二价阴离子活化的 ΔG‡ 增加更大，为 2.1–2.9 kcal/mol EO脱羧。这表明这些取代降低了二阴离子结合位点处的 Q215、Y217 和 R235 侧链的过渡态稳定性。 D37G 和 T100’A 取代导致 ΔG‡ 增加 <1.0 kcal/mol，用于激活 OMPDC 催化的磷酸呋喃糖基截短底物 FO 被亚磷酸二价阴离子脱羧。探究 D37 和 T100’ 取代对 OMPDC 催化 FO 脱羧的 d-甘油 3-磷酸和 d-赤藓糖醇 4-磷酸激活剂动力学参数影响的实验表明，对于通过 D37G 或 T100’A 取代消除的每个 -OH 相互作用，糖-磷酸激活反应的 ΔG‡ 增加约 2.5 kcal/mol。我们得出的结论是，D37 和 T100’ 侧链与核糖基或核糖基样羟基之间的相互作用可用于激活 OMPDC，以催化 OMP、EO 和 FO 的脱羧。
The role of a global, substrate-driven, enzyme conformational change in enabling the extraordinarily large rate acceleration for orotidine 5’-monophosphate decarboxylase (OMPDC)-catalyzed decarboxylation of orotidine 5’-monophosphate (OMP) is examined in experiments that focus on the interactions between OMPDC and the ribosyl hydroxyl groups of OMP. The D37 and T100’ side chains of OMPDC interact, respectively, with the C-3’ and C-2’ hydroxyl groups of enzyme-bound OMP. D37G and T100’A substitutions result in 1.4 kcal/mol increases in the activation barrier ΔG‡ for catalysis of decarboxylation of the phosphodianion truncated substrate 1-(β-D-erythrofuranosyl)orotic acid (EO), but in larger 2.1–2.9 kcal/mole increases in ΔG‡ for decarboxylation of OMP, and for phosphite dianion-activated decarboxylation of EO. This shows that these substitutions reduce transition state stabilization by the Q215, Y217 and R235 side chain at the dianion binding site. The D37G and T100’A substitutions result in <1.0 kcal/mol increases in ΔG‡ for activation of OMPDC-catalyzed decarboxylation of the phosphoribofuranosyl truncated substrate FO by phosphite dianion. Experiments to probe the effect of D37 and T100’ substitutions on the kinetic parameters for d-glycerol 3-phosphate and d-erythritol 4-phosphate activators of OMPDC-catalyzed decarboxylation of FO show that ΔG‡ for sugar-phosphate activated reactions is increased by ca 2.5 kcal/mol for each −OH interaction eliminated by D37G or T100’A substitutions. We conclude that the interactions between the D37 and T100’ side chains and ribosyl, or ribosyl-like hydroxyl groups are utilized to activate OMPDC for catalysis of decarboxylation of OMP, EO, and FO.
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影响因子：
2.9
作者：
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通讯作者：
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