Novel thermostable glycosidases in the extracellular matrix of the terrestrial cyanobacterium Nostoc commune.
Novel thermostable glycosidases in the extracellular matrix of the terrestrial cyanobacterium Nostoc commune.
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DOI：
10.2323/jgam.54.243
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发表时间：
2008-10
期刊：
影响因子：
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通讯作者：
F. Morsy;S. Kuzuha;Yayoi Takani;T. Sakamoto
中科院分区：
文献类型：
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作者：
F. Morsy;S. Kuzuha;Yayoi Takani;T. Sakamoto
蓝细菌Nostoc commune适应陆地环境并形成可见的菌落，其中细胞包埋在胞外多糖（EPS）中，胞外多糖在该生物体的极端干燥耐受性中起着至关重要的作用。当自然菌落浸入水中时，菌落在2天内发生降解，N。将公社细胞释放到水中。水解各种N.使用人造硝基苯基连接的糖作为底物来检查公社级分。从水溶性级分纯化的β-D-葡糖苷酶耐煮沸20分钟。β-D-葡萄糖苷酶的分子量为20 kDa，根据其N-末端氨基酸序列鉴定为蓝藻成束蛋白。纯化了水溶性组分中的36-kDa主要蛋白，发现该蛋白的N-末端氨基酸序列与N.公社。该WspA蛋白还显示耐热β-D-半乳糖苷酶活性。细胞外基质中的成束蛋白和WspA可能在细胞周围的EPS的水解中发挥作用，可能有助于细胞的分散，从而扩大该蓝细菌的菌落。
The cyanobacterium Nostoc commune is adapted to the terrestrial environment and forms a visible colony in which the cells are embedded in extracellular polysaccharides (EPSs), which play a crucial role in the extreme desiccation tolerance of this organism. When natural colonies were immersed in water, degradation of the colonies occurred within 2 days and N. commune cells were released into the water. The activities that hydrolyze glycoside bonds in various N. commune fractions were examined using artificial nitrophenyl-linked sugars as substrates. A beta-D-glucosidase purified from the water-soluble fraction was resistant to 20 min of boiling. The beta-D-glucosidase, with a molecular mass of 20 kDa, was identified as a cyanobacterial fasciclin protein based on its N-terminal amino-acid sequence. The 36-kDa major protein in the water-soluble fraction was purified, and the N-terminal amino-acid sequence of the protein was found to be identical to that of the water-stress protein (WspA) of N. commune. This WspA protein also showed heat-resistant beta-D-galactosidase activity. The fasciclin protein and WspA in the extracellular matrix may play a role in the hydrolysis of the EPSs surrounding the cells, possibly as an aid in the dispersal of cells, thus expanding the colonies of this cyanobacterium.