A precise swaying map for how promiscuous cellobiose-2-epimerase operate bi-reaction

作者：Feng, Yinghui; Lyu, Xiaomei; Cong, Yalong; Miao, Tingwei; Fang, Bohuan; Zhang, Chuanxi; Shen, Qiang; Matthews, Melissa; Fisher, Andrew J.; Zhang, John Z. H.; Zhang, Lujia^*; Yang, Ruijin^*

来源：International Journal of Biological Macromolecules, 2023, 253: 127093.

DOI：10.1016/j.ijbiomac.2023.127093

• Promiscuous enzyme
• Cellobiose 2-epimerase
• Cis -enediol intermediate

Promiscuous enzymes play a crucial role in organism survival and new reaction mining. However, compre-hensive mapping of the catalytic and regulatory mechanisms hasn't been well studied due to the characteristic complexity. The cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus (CsCE) with complex epimeri-zation and isomerization was chosen to comprehensively investigate the promiscuous mechanisms. Here, the catalytic frame of ring-opening, cis-enediol mediated catalysis and ring-closing was firstly determined. To map the full view of promiscuous CE, the structure of CsCE complex with the isomerized product glucopyranosyl-beta 1,4-fructose was determined. Combined with computational calculation, the promiscuity was proved a precise cooperation of the double subsites, loop rearrangement, and intermediate swaying. The flexible loop was like a gear, whose structural reshaping regulates the sway of the intermediates between the two subsites of H377-H188 and H377-H247, and thus regulates the catalytic directions. The different protonated states of cis-enediol in-termediate catalyzed by H188 were the key point for the catalysis. The promiscuous enzyme tends to utilize all elements at hand to carry out the promiscuous functions.

• 单位
  上海交通大学; 江南大学