Regulation of invertase: a suite of transcriptional and post-transcriptional mechanisms
Regulation of invertase: a suite of transcriptional and post-transcriptional mechanisms
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DOI：
10.1071/fp06227
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发表时间：
2007-01-01
影响因子：
3
通讯作者：
Koch, Karen E.
中科院分区：
文献类型：
--
作者：
Huang, Li-Fen;Bocock, Philip N.;Koch, Karen E.
最近的证据表明，几种机制可以改变转化酶的活性，从而影响植物的蔗糖代谢和资源分配。其中一种机制是蛋白酶前体囊泡（PPV）中至少一些液泡转化酶的区隔化，它们的保留可以控制液泡的递送时间，从而控制活性。PPV是一种来源于内质网的小体，它可以隔离液泡结合蛋白（如转化酶和蛋白酶前体）的子集，根据发育或环境信号将其释放到酸性液泡中。另一个新发现的转化酶效应物是壁相关激酶2 (wall-associated kinase 2, WAK2)，它可以调节拟南芥中特定的空泡转化酶（AtvacINV1），并在渗透物供应受限时改变根的生长。WAK的理想定位是感知细胞壁和质膜之间界面的变化（如肿胀），因为每个WAK的n端延伸到细胞壁基质中（假设果胶关联），c端具有细胞质丝氨酸/苏氨酸激酶结构域（信号传导）。还有其他的转化酶控制途径是由多种激酶和磷酸酶提供的，与糖、病原体、ABA和其他激素的多种传感系统的输入一致。不同酸转化酶转录物对糖的反应不同，调控机制也可能不同。在糖抑制转化酶中已经观察到一定程度的己糖激酶参与和独特的动力学，但迄今为止尚未观察到更常见的糖诱导形式。转化酶基因表达的另一种调控手段在于3'非翻译区的多个DST （Down STream）元件，用于最快速抑制的转化酶。类似的序列最初在小生长素上升rna （SAUR）中被发现，它们介导mRNA的快速周转。最后，转化酶抑制剂、果苷酶细胞壁和液泡抑制剂（分别为CIF和VIF）与果胶甲基酯酶抑制剂（PMEI）仅从序列上无法区分；然而，最近的证据表明，结合特异性可能是由短的n端区域的灵活性决定的。这些最近描述的过程增加了一套调节机制，通过这些机制，转化酶——以及因此，蔗糖代谢和资源分配——可以在植物中被改变。
Recent evidence indicates that several mechanisms can alter invertase activity and, thus, affect sucrose metabolism and resource allocation in plants. One of these mechanisms is the compartmentalisation of at least some vacuolar invertases in precursor protease vesicles (PPV), where their retention could control timing of delivery to vacuoles and hence activity. PPV are small, ER-derived bodies that sequester a subset of vacuolar-bound proteins (such as invertases and protease precursors) releasing them to acid vacuoles in response to developmental or environmental signals. Another newly-identified effector of invertases is wall-associated kinase 2 (WAK2), which can regulate a specific vacuolar invertase in Arabidopsis (AtvacINV1) and alter root growth when osmolyte supplies are limiting. WAKs are ideally positioned to sense changes in the interface between the cell wall and plasma membrane (such as turgor), because the N-terminus of each WAK extends into the cell wall matrix (where a pectin association is hypothesised) and the C-terminus has a cytoplasmic serine/ threonine kinase domain (signalling). Still other avenues of invertase control are provided by a diverse group of kinases and phosphatases, consistent with input from multiple sensing systems for sugars, pathogens, ABA and other hormones. Mechanisms of regulation may also vary for the contrasting sugar responses of different acid invertase transcripts. Some degree of hexokinase involvement and distinctive kinetics have been observed for the sugar-repressed invertases, but not for the more common, sugar-induced forms examined thus far. An additional means of regulation for invertase gene expression lies in the multiple DST (Down STream) elements of the 3' untranslated region for the most rapidly repressed invertases. Similar sequences were initially identified in small auxin-up RNAs (SAUR) where they mediate rapid mRNA turnover. Finally, the invertase inhibitors, cell wall- and vacuolar inhibitors of fructosidase (CIF and VIF, respectively) are indistinguishable by sequence alone from pectin methylesterase inhibitors (PMEI); however, recent evidence suggests binding specificity may be determined by flexibility of a short, N-terminal region. These recently characterised processes increase the suite of regulatory mechanisms by which invertase - and, thus, sucrose metabolism and resource partitioning - can be altered in plants.