Xyloglucan endotransglucosylase/hydrolases (XTHs) are inactivated by binding to glass and cellulosic surfaces, and released in active form by a heat-stable polymer from cauliflower florets.
Xyloglucan endotransglucosylase/hydrolases (XTHs) are inactivated by binding to glass and cellulosic surfaces, and released in active form by a heat-stable polymer from cauliflower florets.
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DOI：
10.1016/j.jplph.2017.07.022
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发表时间：
2017-11
影响因子：
4.3
通讯作者：
Fry SC
中科院分区：
文献类型：
--
作者：
Sharples SC;Nguyen-Phan TC;Fry SC
木葡聚糖内切转葡糖基酶（XET）活性是XTH蛋白的主要活性，其切割并重新连接植物细胞壁中的半纤维素链，有助于壁组装和生长调节。在纯化过程中，XTH经常失去XET活性，然而，通过用某些冷水可提取的热稳定聚合物（CHP）（例如来自花椰菜小花）处理，XET活性得以恢复。目前尚不清楚CHP中存在的XTH激活因子（XAF）是否通过促进（例如变构）XET活性或通过重新溶解隔离的XTH蛋白来起作用。我们现在表明，XTH在稀溶液中结合到不同的表面（如玻璃和纤维素），和CHP可以重新溶解结合的酶，重新激活it. Cell壁制备的花椰菜小花，绿豆芽和拟南芥细胞悬浮培养物中的每一个包含内源性的，紧密结合的，无活性的XTH，这同样迅速溶解（0.5小时内），从而激活花椰菜XAF。我们提出了一个方便的定量测定XAF作用于本机隔离XTH的拟南芥细胞壁，使用此测定，我们表明，从所有植物的CHP测试具有XAF活性。不同CHP的XAF活性与其电导率无关，表明这种活性不是简单的离子效应。花椰菜CHP的XAF作用被NaCl增强，尽管单独的NaCl比具有类似电导率的CHP溶液有效得多，证实花椰菜聚合物不简单地发挥盐效应。我们认为XAF是XET作用的内源性调节剂，调节体内细胞壁松动和/或组装。
Xyloglucan endotransglucosylase (XET) activity, which cuts and re-joins hemicellulose chains in the plant cell wall, contributing to wall assembly and growth regulation, is the major activity of XTH proteins. During purification, XTHs often lose XET activity which, however, is restored by treatment with certain cold-water-extractable, heat-stable polymers (CHPs), e.g. from cauliflower florets. It was not known whether the XTH-activating factor (XAF) present in CHPs works by promoting (e.g. allosterically) XET activity or by re-solubilising sequestered XTH proteins. We now show that XTHs in dilute solution bind to diverse surfaces (e.g. glass and cellulose), and that CHPs can re-solubilise the bound enzyme, re-activating it. Cell walls prepared from cauliflower florets, mung bean shoots and Arabidopsis cell-suspension cultures each contained endogenous, tightly bound, inactive XTHs, which were likewise rapidly solubilised (within 0.5 h) and thus activated by cauliflower XAF. We present a convenient quantitative assay for XAF acting on the native sequestered XTHs of Arabidopsis cell walls; using this assay, we show that CHPs from all plants tested possess XAF activity. The XAF activity of diverse CHPs does not correlate with their conductivity, showing that this activity is not a simple ionic effect. The XAF action of cauliflower CHPs was augmented by NaCl, although NaCl alone was much less effective than a CHP solution of similar conductivity, confirming that the cauliflower polymers did not simply exert a salt effect. We suggest that XAF is an endogenous regulator of XET action, modulating cell-wall loosening and/or assembly in vivo.
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胡杨 XTH 过表达通过转基因烟草植物叶片肉质的发育增强耐盐性
影响因子：
6.9
作者：
Han Y;Wang W;Sun J;Ding M;Zhao R;Deng S;Wang F;Hu Y;Wang Y;Lu Y;Du L;Hu Z;Diekmann H;Shen X;Polle A;Chen S
通讯作者：
Chen S
影响因子：
4.1
作者：
FRY, SC;SMITH, RC;MATTHEWS, KJ
通讯作者：
MATTHEWS, KJ
影响因子：
4.3
作者：
Takeda, T;Fry, SC
通讯作者：
Fry, SC
影响因子：
5.2
作者：
Almeida, Domingos P. F.;Huber, Donald J.
通讯作者：
Huber, Donald J.
影响因子：
6.9
作者：
GOLDBERG, R;PIERRON, M;MUTAFTSCHIEV, S
通讯作者：
MUTAFTSCHIEV, S