National Glycoengineering Research Center, Shandong University, No. 72 Binhai Road, Qingdao, 266237, China.
State Key Lab of Microbial Technology, Shandong University, No. 72 Binhai Road, Qingdao, 266237, China.
Mol Biol Rep. 2019 Oct;46(5):5443-5454. doi: 10.1007/s11033-019-04999-x. Epub 2019 Jul 29.
PoCel12A, PoCel12B, and PoCel12C are genes that encode glycoside hydrolase family 12 (GH12) enzymes in Penicillium oxalicum. PoCel12A and PoCel12B are typical GH12 enzymes that belong to fungal subfamilies 12-1 and 12-2, respectively. PoCel12C contains a low-complexity region (LCR) domain, which is not found in PoCel12A or PoCel12B and independent of fungal subfamily 12-1 or 12-2. Recombinant enzymes (named rCel12A, rCel12B and rCel12C) demonstrate existing diversity in the substrate specificities. Although most members in GH family 12 are typical endoglucanases and preferentially hydrolyze β-1,4-glucan (e.g., carboxymethylcellulose), recombinant PoCel12A is a non-typical endo-(1-4)-β-glucanase; it preferentially hydrolyzes mix-linked β-glucan (barley β-glucan, β-1,3-1,4-glucan) and slightly hydrolyzes β-1,4-glucan (carboxymethylcellulose). Recombinant PoCel12B possesses a significantly high activity against xyloglucan. A specific activity of rCel12B toward xyloglucan (239 µmol/min/mg) is the second-highest value known. Recombinant PoCel12C shows low activity toward β-glucan, carboxymethylcellulose, or xyloglucan. All three enzymes can degrade phosphoric acid-swollen cellulose (PASC). However, the hydrolysis products toward PASC by enzymes are different: the main hydrolysis products are cellotriose, cellotetraose, and cellobiose for rCel12A, rCel12B, and rCel12C, correspondingly. A synergistic action toward PASC among rCel12A and rCel12B is observed, thereby suggesting a potential application for preparing enzyme cocktails used in lignocellulose hydrolysis.
PoCel12A、PoCel12B 和 PoCel12C 是编码草酸青霉糖苷水解酶家族 12（GH12）酶的基因。PoCel12A 和 PoCel12B 是典型的 GH12 酶，分别属于真菌亚家族 12-1 和 12-2。PoCel12C 含有一个低复杂度区域（LCR）结构域，该结构域在 PoCel12A 或 PoCel12B 中不存在，也不依赖于真菌亚家族 12-1 或 12-2。重组酶（分别命名为 rCel12A、rCel12B 和 rCel12C）显示出底物特异性的多样性。尽管 GH12 家族的大多数成员是典型的内切葡聚糖酶，优先水解β-1,4-葡聚糖（例如羧甲基纤维素），但重组 PoCel12A 是非典型的内切-(1-4)-β-葡聚糖酶；它优先水解混合连接的β-葡聚糖（大麦β-葡聚糖，β-1,3-1,4-葡聚糖），并轻微水解β-1,4-葡聚糖（羧甲基纤维素）。重组 PoCel12B 对木葡聚糖具有显著的高活性。rCel12B 对木葡聚糖的比活性（239µmol/min/mg）是已知的第二高值。重组 PoCel12C 对β-葡聚糖、羧甲基纤维素或木葡聚糖的活性较低。三种酶都可以降解磷酸化膨胀纤维素（PASC）。然而，酶对 PASC 的水解产物不同：rCel12A、rCel12B 和 rCel12C 对 PASC 的主要水解产物分别为纤维三糖、纤维四糖和纤维二糖。rCel12A 和 rCel12B 对 PASC 表现出协同作用，这表明它们在木质纤维素水解中制备酶混合物方面有潜在的应用。
