A novel mechanism of xylan binding by a lectin-like module from Streptomyces lividans xylanase 10A
A novel mechanism of xylan binding by a lectin-like module from Streptomyces lividans xylanase 10A
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DOI：
10.1042/0264-6021:3500933
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发表时间：
2000-09-15
影响因子：
4.1
通讯作者：
Kilburn, DG
中科院分区：
文献类型：
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作者：
Boraston, AB;Tomme, P;Kilburn, DG
变铅青链霉菌木聚糖酶10A的C-末端模块是家族13碳水化合物结合模块（CBM 13）。CBM 13与单糖和低聚糖结合，结合常数约为1 x 10（2）M-1- 1 x 10（3）M-1。它似乎只对吡喃糖有特异性。CBM 13结合不溶性和可溶性木聚糖、综纤维素、茯苓多糖、地衣多糖、阿拉伯半乳聚糖和海带多糖。与可溶性木聚糖结合的缔合常数为（6.2 +/-0.6）X 10（3）/mol木聚糖聚合物。定点突变表明CBM 13上的三个功能位点参与与可溶性木聚糖的结合。这些位点在序列上与蓖麻毒素B链的α、β和γ位点相似，并且预测具有相似的结构，蓖麻毒素B链也在家族13中。CBM 13上的单个结合位点对可溶性木聚糖的亲和力仅约为（0.5 +/-0.1）× 10（3）/mol木聚糖。CBM 13与可溶性木聚糖的结合涉及三个结合位点之间的加和和协同相互作用。对于CBM结合多糖，这种结合机制以前没有报道过。CBM 13是第一个要详细描述的来自家族13的细菌模块。
The C-terminal module of xylanase 10A from Streptomyces lividans is a family 13 carbohydrate-binding module (CBM13). CBM13 binds mono- and oligo-saccharides with association constants of approximate to 1 x 10(2) M-1-l x 10(3) M-1. It appears to be specific only for pyranose sugars. CBM13 binds insoluble and soluble xylan, holocellulose, pachyman, lichenan, arabinogalactan and laminarin. The association constant for binding to soluble xylan is (6.2 +/- 0.6) x 10(3)/mol of xylan polymer. Site-directed mutation indicates the involvement of three functional sites on CBM13 in binding to soluble xylan. The sites are similar in sequence, and are predicted to have similar structures, to the alpha, beta and gamma sites of ricin toxin B-chain, which is also in family 13. The affinity of a single binding site on CBM13 for soluble xylan is only approximate to (0.5 +/- 0.1) x 10(3)/mol of xylan. The binding of CBM13 to soluble xylan involves additive and co-operative interactions between the three binding sites. This mechanism of binding has not previously been reported for CBMs binding polysaccharides. CBM13 is the first bacterial module from family 13 to be described in detail.