Splicing kinase SRPK1 conforms to the landscape of its SR protein substrate.
Splicing kinase SRPK1 conforms to the landscape of its SR protein substrate.
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DOI：
10.1021/bi4010864
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发表时间：
2013-10-29
期刊：
影响因子：
2.9
通讯作者：
Adams, Joseph A.
中科院分区：
文献类型：
--
作者：
Aubol, Brandon E.;Jamros, Michael A.;McGlone, Maria L.;Adams, Joseph A.
SR蛋白的剪接功能受其c端RS（富含精氨酸-丝氨酸）结构域的多位点磷酸化调控。SRPK1已被证明通过一种定向机制磷酸化原型SR蛋白SRSF1，在这种定向机制中，由精氨酸两侧的11条丝氨酸依次从激酶结构域大叶的对接槽进入活性位点。虽然这一过程预计会在较长的精氨酸-丝氨酸重复序列（≥8）上进行，但许多SR蛋白只包含1-4个二肽的较小重复序列，这就提出了RS结构域结构如何被磷酸化的问题。为了解决这个问题，我们研究了Tra2β的剪接变体，该变体包含一个具有短精氨酸-丝氨酸重复序列的c端RS结构域[Tra2β（ΔN）]。我们发现SRPK1选择性地磷酸化RS结构域c端附近的几个丝氨酸。SRPK1使用Tra2β的分配机制（ΔN），其中限速步骤是蛋白质底物的解离，而不是像SRSF1那样的核苷酸交换。虽然有效的SRSF1磷酸化需要一个功能正常的对接槽，但这个保守的结构元件对于Tra2β（ΔN）磷酸化是必不可少的。这些机制上的巨大变化可能解释了与SRSF1相比，Tra2β（ΔN）的净周转率较慢的原因，并可能表明具有不同精氨酸-丝氨酸谱的SR蛋白在磷酸化方面存在根本差异。总的来说，这些数据表明SRPK1通过灵活的动力学机制和选择性使用保守对接槽来符合RS结构域结构的变化。
The splicing function of SR proteins is regulated by multisite phosphorylation of their C-terminal RS (arginine-serine rich) domains. SRPK1 has been shown to phosphorylate the prototype SR protein SRSF1 using a directional mechanism in which eleven serines flanked by arginines are sequentially feed from a docking groove in the large lobe of the kinase domain to the active site. While this process is expected to operate on lengthy arginine-serine repeats (≥8), many SR proteins contain smaller repeats of only 1–4 dipeptides raising the question of how alternate RS domain configurations are phosphorylated. To address this, we studied a splice variant of Tra2β that contains a C-terminal RS domain with short arginine-serine repeats [Tra2β(ΔN)]. We showed that SRPK1 selectively phosphorylates several serines near the C-terminus of the RS domain. SRPK1 uses a distributive mechanism for Tra2β(ΔN) where the rate-limiting step is dissociation of the protein substrate rather than nucleotide exchange as in the case of SRSF1. While a functioning docking groove is required for efficient SRSF1 phosphorylation, this conserved structural element is dispensable for Tra2β(ΔN) phosphorylation. These large shifts in mechanism are likely to account for the slower, net turnover rate of Tra2β(ΔN) compared to SRSF1 and may signal fundamental differences in phosphorylation among SR proteins with distinctive arginine-serine profiles. Overall, these data indicate that SRPK1 conforms to changes in RS domain architecture using a flexible kinetic mechanism and selective usage of a conserved docking groove.
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影响因子：
56.9
作者：
Valcarcel, J;Gaur, RK;Green, MR
通讯作者：
Green, MR
DOI：
10.1073/pnas.1017700108
发表时间：
2011-05-17
影响因子：
11.1
作者：
Cho, Suhyung;Hoang, Amy;Ghosh, Gourisankar
通讯作者：
Ghosh, Gourisankar
影响因子：
2.9
作者：
Aubol, Brandon E.;Adams, Joseph A.
通讯作者：
Adams, Joseph A.
影响因子：
16
作者：
Ngo, JCK;Chakrabarti, S;Ghosh, G
通讯作者：
Ghosh, G
影响因子：
3.5
作者：
Stoilov, P;Daoud, R;Stamm, S
通讯作者：
Stamm, S