Characterization of AIR9 - a novel plant microtubule-associated protein that marks the division plane

AIR9 的表征 - 一种标记分裂平面的新型植物微管相关蛋白

• 批准号: BB/E022634/1
• 负责人: Clive Lloyd
• 金额: $ 46.48万
• 依托单位: John Innes Centre
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FE022634%2F1
• 关键词: Characterization; AIR9; novel; plant; microtubule

Plant cells do not crawl around like animal cells. Instead, cells are organized in tissues and organs according to the plane in which cross-walls are laid down between cells. Curiously, the division plane is predicted before division actually takes place by a ring of microtubules (called the preprophase band) that forms at the inner surface of the plasma membrane. After the nucleus has divided, a new cross-wall is put down between the two daughter nuclei and this attaches to the parental cell wall at the exact site forecast by the preprophase band. However, the band disappears before division and we have no idea of how the predicted plane of cell division can be 'memorized' in the period until the cross-wall forms. Possibly the band leaves behind a marker(s) on the cell surface - a 'molecular tidemark'? In a search for novel proteins that might bind, and hence regulate, plant microtubules, we discovered a large protein named AIR9. By coupling it to a fluorescent marker, we can see that this protein decorates the preprophase band and then disappears along with the band's microtubules as the cell starts to divide. The new cross-wall starts off in the centre of the cell and grows outwards until it touches the parental cell wall. The moment this cross-wall contacts the former site of the preprophase band we can see that the fluorescent AIR9 signal reappears upon the cell surface. This suggests that an AIR9-binding protein was left behind by the preprophase band of microtubules and is recognized for a second time when the cross-wall completes its predicted journey. AIR9 therefore offers one of the first handles on this crucial phase in plant cell division. We will see if AIR9 binds directly to microtubules or needs another partner. We have already found that AIR9 is likely to bind to two interesting proteins (one involved in cell wall synthesis, the other a motor that travels along microtubules) and we propose to confirm this. Other experiments will be aimed at examining mutations in this protein as well as experimentally inducing cells to produce too much or too little of the protein. We will alter the protein so that its regulatory sites cannot be modified by the cell (by phosphorylation) to see if the protein can be made to function at inappropriate stages of the cell's division cycle. The defects that arise from these treatments should provide valuable insights into how AIR9 functions in plants.

植物细胞不像动物细胞那样爬行。相反，细胞在组织和器官中是根据细胞之间的交叉壁平面组织起来的。奇怪的是，在分裂发生之前，分裂平面是由一圈微管（称为前期带）预测的，这些微管在质膜的内表面形成。细胞核分裂后，在两个子细胞核之间形成一个新的交叉壁，并在前期带预测的确切位置附着在亲本细胞壁上。然而，在分裂之前，条带消失了，我们不知道在交叉壁形成之前，细胞分裂的预测平面是如何被“记忆”的。可能这个条带会在细胞表面留下一个标记——一个“分子潮标”？在寻找可能结合并因此调节植物微管的新蛋白质的过程中，我们发现了一种名为AIR9的大蛋白质。通过将其与荧光标记结合，我们可以看到这种蛋白质修饰了前期带，然后在细胞开始分裂时随着带的微管一起消失。新的交叉壁从细胞中心开始向外生长，直到接触到亲本细胞壁。当这个交叉壁接触到前前期带的位置时，我们可以看到荧光AIR9信号在细胞表面重新出现。这表明一个air9结合蛋白被微管的前期带留下，并在交叉壁完成其预测的旅程时被第二次识别。因此，AIR9在植物细胞分裂的这个关键阶段提供了第一个处理。我们将观察AIR9是直接与微管结合还是需要另一个伙伴。我们已经发现，AIR9可能与两种有趣的蛋白质结合（一种参与细胞壁合成，另一种是沿着微管移动的马达），我们打算证实这一点。其他的实验将旨在检测这种蛋白质的突变，以及通过实验诱导细胞产生过多或过少的蛋白质。我们将改变这种蛋白质，使其调控位点不能被细胞（通过磷酸化）修改，看看这种蛋白质是否能在细胞分裂周期的不适当阶段发挥作用。这些处理产生的缺陷应该为了解AIR9在植物中的功能提供有价值的见解。