Caefer Danielle M, Phan Nhat Q, Liddle Jennifer C, Balsbaugh Jeremy L, O'Shea Joseph P, Tzingounis Anastasios V, Schwartz Daniel
Department of Physiology and Neurobiology, University of Connecticut, Storrs, CT, United States.
Center for Open Research Resources and Equipment, Proteomics and Metabolomics Facility, University of Connecticut, Storrs, CT, United States.
Front Mol Biosci. 2022 Apr 19;9:850661. doi: 10.3389/fmolb.2022.850661. eCollection 2022.
Okur-Chung Neurodevelopmental Syndrome (OCNDS) is caused by heterozygous mutations to the gene, which encodes the alpha subunit of protein kinase CK2. The most frequently occurring mutation is lysine 198 to arginine (K198R). To investigate the impact of this mutation, we first generated a high-resolution phosphorylation motif of CK2, including the first characterization of specificity for tyrosine phosphorylation activity. A second high resolution motif representing CK2 substrate specificity was also generated. Here we report the impact of the OCNDS associated CK2 mutation. Contrary to prior speculation, the mutation does not result in a complete loss of function, but rather shifts the substrate specificity of the kinase. Broadly speaking the mutation leads to 1) a decreased preference for acidic residues in the +1 position, 2) a decreased preference for threonine phosphorylation, 3) an increased preference for tyrosine phosphorylation, and 4) an alteration of the tyrosine phosphorylation specificity motif. To further investigate the result of this mutation we have developed a probability-based scoring method, allowing us to predict shifts in phosphorylation in the K198R mutant relative to the wild type kinase. As an initial step we have applied the methodology to the set of axonally localized ion channels in an effort to uncover potential alterations of the phosphoproteome associated with the OCNDS disease condition.
奥库尔-钟神经发育综合征（OCNDS）由该基因的杂合突变引起，该基因编码蛋白激酶CK2的α亚基。最常见的突变是赖氨酸198突变为精氨酸（K198R）。为了研究这种突变的影响，我们首先生成了CK2的高分辨率磷酸化基序，包括酪氨酸磷酸化活性特异性的首次表征。还生成了代表CK2底物特异性的第二个高分辨率基序。在此我们报告与OCNDS相关的CK2突变的影响。与先前的推测相反，该突变不会导致功能完全丧失，而是会改变激酶的底物特异性。一般来说，该突变导致：1）对+1位酸性残基的偏好降低；2）对苏氨酸磷酸化的偏好降低；3）对酪氨酸磷酸化的偏好增加；4）酪氨酸磷酸化特异性基序的改变。为了进一步研究这种突变的结果，我们开发了一种基于概率的评分方法，使我们能够预测K198R突变体相对于野生型激酶磷酸化的变化。作为第一步，我们已将该方法应用于一组轴突定位的离子通道，以揭示与OCNDS疾病状态相关的磷酸化蛋白质组的潜在变化。
