A novel intracellular dextranase derived from Paenibacillus sp. 598K with an ability to degrade cycloisomaltooligosaccharides.
A novel intracellular dextranase derived from Paenibacillus sp. 598K with an ability to degrade cycloisomaltooligosaccharides.
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一种源自类芽孢杆菌属的新型细胞内葡聚糖酶。
DOI：
10.1007/s00253-019-09965-y
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发表时间：
2019
影响因子：
5
通讯作者：
Funane K
中科院分区：
文献类型：
--
作者：
Mizushima D;Miyazaki T;Shiwa Y;Kimura K;Suzuki S;Fujita N;Yoshikawa H;Kimura A;Kitamura S;Hara H;Funane K
Paenibacillussp. 598K在培养中从葡聚糖和淀粉中产生环异麦芽寡糖（CIs）。CIs是由7个或更多的α-(1→6)-连接-d-葡萄糖残基组成的环状低聚糖。胞外酶CI葡聚糖转移酶（PsCITase）是糖苷水解酶家族66的成员，催化CI生产的最后阶段，主要生产环异芽糖七糖。我们从paenibacillussp中发现了一种新的胞内ci降解葡聚糖酶（PsDEX598）。598 k。69.7 kda重组蛋白PsDEX598不能消化异麦芽糖四糖或较短的低聚异麦芽糖，但能消化较长的异麦芽糖七糖。它也能更好地消化环异麦芽糖七糖糖、环异麦芽糖醛酸糖和环异麦芽糖醛酸糖，而对环异麦芽糖醛酸糖、环异麦芽糖醛酸糖和环异麦芽糖十二糖醛酸糖，以及α-(1→6)-d葡聚糖的葡聚糖。当培养基中添加环异麦芽糖七糖或葡聚糖，但不添加低聚异麦芽糖（异麦芽糖、异麦芽糖和葡萄糖的混合物）、淀粉或葡萄糖时，在细胞内产生PsDEX598。菌株598K的全基因组DNA序列表明，该菌株含有2个糖苷水解酶家族66的酶基因（PsCITase和PsDEX598），其中PsDEX598是该菌株中唯一的葡聚糖酶。PsDEX598不含任何碳水化合物结合模块（CBMs），与其他66家族葡聚糖酶相似度较低（< 30%），预测该酶的催化氨基酸为Asp191、Asp303和Glu368。strainPaenibacillussp。598K似乎吸收了CI-7，因此这些发现表明这种细菌可以利用细胞内的葡聚糖酶降解CIs，从而利用它们作为生长的碳源。
Paenibacillussp. 598K produces cycloisomaltooligosaccharides (CIs) in culture from dextran and starch. CIs are cyclic oligosaccharides consisting of seven or more α-(1 → 6)-linked-d-glucose residues. The extracellular enzyme CI glucanotransferase (PsCITase), which is the member of glycoside hydrolase family 66, catalyzes the final stage of CI production and produces mainly cycloisomaltoheptaose. We have discovered a novel intracellular CI-degrading dextranase (PsDEX598) fromPaenibacillussp. 598K. The 69.7-kDa recombinant PsDEX598 does not digest isomaltotetraose or shorter isomaltooligosaccharides, but digests longer ones of at least up to isomaltoheptaose. It also digests oligoCIs of cycloisomaltoheptaose, cycloisomaltooctaose, and cycloisomaltononaose better than it does with megaloCIs of cycloisomaltodecaose, cycloisomaltoundecaose, and cycloisomaltododecaose, as well as an α-(1 → 6)-d-glucan of dextran 40. PsDEX598 is produced intracellularly when culture medium is supplemented with cycloisomaltoheptaose or dextran, but not with isomaltooligosaccharides (a mixture of isomaltose, isomaltotriose, and panose), starch, or glucose. The whole genomic DNA sequence of the strain 598K implies that it harbors two genes for enzymes belonging to glycoside hydrolase family 66 (PsCITase and PsDEX598), and PsDEX598 is the only dextranase in the strain. PsDEX598 does not have any carbohydrate-binding modules (CBMs) and has a low similarity (< 30%) with other family 66 dextranases, and the catalytic amino acids of this enzyme are predicted to be Asp191, Asp303, and Glu368. The strainPaenibacillussp. 598K appears to take up CI-7, so these findings indicate that this bacterium can degrade CIs using a dextranase within the cells and so utilize them as a carbon source for growth.