The Role of Substrate Mediated Allostery in the Catalytic Competency of the Bacterial Oligosaccharyltransferase PglB.
The Role of Substrate Mediated Allostery in the Catalytic Competency of the Bacterial Oligosaccharyltransferase PglB.
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DOI：
10.3389/fmolb.2021.740904
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发表时间：
2021
影响因子：
5
通讯作者：
Massi F
中科院分区：
文献类型：
--
作者：
Morgan BR;Massi F
松鼠弯曲杆菌 (Campylobacter lari) 的寡糖转移酶 (PglB) 催化共有序列 N-X-S/T 中天冬酰胺的糖基化，其中 X 是除脯氨酸之外的任何残基。与两种不同底物结合的 PglB 的分子动力学模拟用于表征底物-酶复合物的结构和动力学差异，这可以解释在 +2 位含有苏氨酸而不是丝氨酸的底物所观察到的更高催化效率。我们观察到含苏氨酸的底物比含丝氨酸的底物结合更紧密。由于丝氨酸相对于苏氨酸缺乏甲基，因此含丝氨酸的肽不能像含苏氨酸的底物那样与T316和I572同时稳定地形成范德华相互作用。结果，肽-PglB相互作用不稳定并且周质结构域和外环EL5之间的变构通讯被破坏。这些变化最终导致周质结构域相对于跨膜结构域的重新定向，使得与结合至含苏氨酸的肽的PglB相比，这两个结构域相距更远。与仅具有肽的PglB的结构相比，与肽和脂质连接的寡糖类似物结合的PglB的晶体结构显示出周质结构域在跨膜结构域上的明显闭合，表明催化需要结构域的闭合构象。我们的研究结果表明，与苏氨酸相比，观察到的丝氨酸较低的酶活性是由于 PglB 中结合稳定性较差和结构变化的组合导致的，这些变化影响了形成催化活性状态的能力。这项研究阐明了通过调节动态变构途径实现底物特异性的机制。
The oligosaccharyltransferase of Campylobacter lari (PglB) catalyzes the glycosylation of asparagine in the consensus sequence N-X-S/T, where X is any residue except proline. Molecular dynamics simulations of PglB bound to two different substrates were used to characterize the differences in the structure and dynamics of the substrate-enzyme complexes that can explain the higher catalytic efficiency observed for substrates containing threonine at the +2 position rather than serine. We observed that a threonine-containing substrate is more tightly bound than a serine-containing substrate. Because serine lacks a methyl group relative to threonine, the serine-containing peptide cannot stably form simultaneous van der Waals interactions with T316 and I572 as the threonine-containing substrate can. As a result, the peptide-PglB interaction is destabilized and the allosteric communication between the periplasmic domain and external loop EL5 is disrupted. These changes ultimately lead to the reorientation of the periplasmic domain relative to the transmembrane domain such that the two domains are further apart compared to PglB bound to the threonine-containing peptide. The crystal structure of PglB bound to the peptide and a lipid-linked oligosaccharide analog shows a pronounced closing of the periplasmic domain over the transmembrane domain in comparison to structures of PglB with peptide only, indicating that a closed conformation of the domains is needed for catalysis. The results of our studies suggest that lower enzymatic activity observed for serine versus threonine results from a combination of less stable binding and structural changes in PglB that influence the ability to form a catalytically competent state. This study illustrates a mechanism for substrate specificity via modulation of dynamic allosteric pathways.
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影响因子：
14.9
作者：
Blum M;Chang HY;Chuguransky S;Grego T;Kandasaamy S;Mitchell A;Nuka G;Paysan-Lafosse T;Qureshi M;Raj S;Richardson L;Salazar GA;Williams L;Bork P;Bridge A;Gough J;Haft DH;Letunic I;Marchler-Bauer A;Mi H;Natale DA;Necci M;Orengo CA;Pandurangan AP;Rivoire C;Sigrist CJA;Sillitoe I;Thanki N;Thomas PD;Tosatto SCE;Wu CH;Bateman A;Finn RD
通讯作者：
Finn RD
DOI：
10.1002/prot.340230412
发表时间：
1995-12-01
期刊：
PROTEINS-STRUCTURE FUNCTION AND GENETICS
影响因子：
--
作者：
Frishman, D;Argos, P
通讯作者：
Argos, P
影响因子：
3.5
作者：
Ihssen, Julian;Kowarik, Michael;Thoeny-Meyer, Linda
通讯作者：
Thoeny-Meyer, Linda
影响因子：
4.4
作者：
JORGENSEN, WL;CHANDRASEKHAR, J;KLEIN, ML
通讯作者：
KLEIN, ML
DOI：
10.1126/science.aar7899
发表时间：
2018-04-13
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Braunger K;Pfeffer S;Shrimal S;Gilmore R;Berninghausen O;Mandon EC;Becker T;Förster F;Beckmann R
通讯作者：
Beckmann R