Characterization of a New Cold-Adapted and Salt-Activated Polysaccharide Lyase Family 7 Alginate Lyase from Pseudoalteromonas sp. SM0524.
Characterization of a New Cold-Adapted and Salt-Activated Polysaccharide Lyase Family 7 Alginate Lyase from Pseudoalteromonas sp. SM0524.
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来自假交替单胞菌 SM0524 的新型冷适应和盐激活多糖裂解酶家族 7 藻酸盐裂解酶的表征
DOI：
10.3389/fmicb.2016.01120
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发表时间：
2016
影响因子：
5.2
通讯作者：
Xie BB
中科院分区：
文献类型：
--
作者：
Chen XL;Dong S;Xu F;Dong F;Li PY;Zhang XY;Zhou BC;Zhang YZ;Xie BB
海洋细菌藻酸盐裂解酶在海洋藻酸盐降解和碳循环中起着重要作用。虽然海藻酸裂解酶已被大量研究出来，但有关具有特殊特性的海藻酸裂解酶的报道还比较少。本研究从海洋假交替单胞菌中克隆了编码藻酸盐裂解酶多糖裂解酶家族7(PL7)的基因alyPM。SM0524，并在大肠杆菌中表达。AlyPM与所鉴定的藻酸盐裂解酶序列同源性为41%，表明AlyPM是一种新的PL7酶。AlyPM活性的最适pH为8.5。AlyPM在30℃时活性最高，在5℃时保持最高活性的19%。AlyPM在30℃以上不稳定，Tm低，为37℃。这些数据表明AlyPM是一种冷适应酶。此外，AlyPM是一种盐激活的酶。在0.5-1.2M的氯化钠中，AlyPM的活性比在0M的中高6倍，这可能是由于底物亲和力的显著增加所致，因为在0.5M的氯化钠中AlyPM的Km比在0M的中降低了20多倍。AlyPM较好地降解了聚甘露酸脂，主要释放了二聚体和三聚体。这些数据表明AlyPM是一种新的PL7藻酸内切酶，具有特殊的性质。
Marine bacterial alginate lyases play a role in marine alginate degradation and carbon cycling. Although a large number of alginate lyases have been characterized, reports on alginate lyases with special characteristics are still rather less. Here, a gene alyPM encoding an alginate lyase of polysaccharide lyase family 7 (PL7) was cloned from marine Pseudoalteromonas sp. SM0524 and expressed in Escherichia coli. AlyPM shows 41% sequence identity to characterized alginate lyases, indicating that AlyPM is a new PL7 enzyme. The optimal pH for AlyPM activity was 8.5. AlyPM showed the highest activity at 30°C and remained 19% of the highest activity at 5°C. AlyPM was unstable at temperatures above 30°C and had a low Tm of 37°C. These data indicate that AlyPM is a cold-adapted enzyme. Moreover, AlyPM is a salt-activated enzyme. AlyPM activity in 0.5–1.2 M NaCl was sixfolds higher than that in 0 M NaCl, probably caused by a significant increase in substrate affinity, because the Km of AlyPM in 0.5 M NaCl decreased more than 20-folds than that in 0 M NaCl. AlyPM preferably degraded polymannuronate and mainly released dimers and trimers. These data indicate that AlyPM is a new PL7 endo-alginate lyase with special characteristics.