Glutamylation is a negative regulator of microtubule growth.
Glutamylation is a negative regulator of microtubule growth.
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DOI：
10.1091/mbc.e23-01-0030
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发表时间：
2023-06-01
影响因子：
3.3
通讯作者：
Roll-Mecak, Antonina
中科院分区：
文献类型：
--
作者：
Chen, Jiayi;Roll-Mecak, Antonina
微管是由αβ-微管蛋白二聚体构建的非共价聚合物。无序的C-末端微管蛋白尾部用通过微管蛋白酪氨酸连接酶（TTLL）和羧肽酶（CCP）添加和去除的可变长度的多个谷氨酸链官能化。谷氨酰胺化在稳定的微管阵列如轴丝和轴突中是丰富的，并且其失调导致人类病理学。尽管如此，谷氨酰化对内在微管动力学的影响尚不清楚。在这里，我们产生的微管蛋白与短和长的谷氨酸链，并表明，谷氨酰化减缓微管生长的速度，并增加作为一个功能的谷氨酰化水平的灾难。这意味着细胞中谷氨酰化微管的更高稳定性是由于效应物。有趣的是，EB 1受谷氨酰化的影响最小，因此可以报告未修饰和谷氨酰化微管的生长速率。最后，我们表明，谷氨酸去除CCP 1和5是协同的，并优先发生在可溶性微管蛋白，不像TTLL酶，更喜欢微管。这种底物偏好建立了一种不对称性，一旦微管解聚，释放的微管蛋白被重置为较少修饰的状态，而聚合的微管蛋白积累了谷氨酰化标记。我们的工作表明，对无序微管蛋白尾部的修饰可以直接影响微管动力学，并进一步加深了我们对微管蛋白编码机制基础的理解。
Microtubules are noncovalent polymers built from αβ-tubulin dimers. The disordered C-terminal tubulin tails are functionalized with multiple glutamate chains of variable lengths added and removed by tubulin tyrosine ligases (TTLLs) and carboxypeptidases (CCPs). Glutamylation is abundant on stable microtubule arrays such as in axonemes and axons, and its dysregulation leads to human pathologies. Despite this, the effects of glutamylation on intrinsic microtubule dynamics are unclear. Here we generate tubulin with short and long glutamate chains and show that glutamylation slows the rate of microtubule growth and increases catastrophes as a function of glutamylation levels. This implies that the higher stability of glutamylated microtubules in cells is due to effectors. Interestingly, EB1 is minimally affected by glutamylation and thus can report on the growth rates of both unmodified and glutamylated microtubules. Finally, we show that glutamate removal by CCP1 and 5 is synergistic and occurs preferentially on soluble tubulin, unlike TTLL enzymes that prefer microtubules. This substrate preference establishes an asymmetry whereby once the microtubule depolymerizes, the released tubulin is reset to a less-modified state, while polymerized tubulin accumulates the glutamylation mark. Our work shows that a modification on the disordered tubulin tails can directly affect microtubule dynamics and furthers our understanding of the mechanistic underpinnings of the tubulin code.