Abdel-Fattah Wael, Jablonowski Daniel, Di Santo Rachael, Thüring Kathrin L, Scheidt Viktor, Hammermeister Alexander, Ten Have Sara, Helm Mark, Schaffrath Raffael, Stark Michael J R
Centre for Gene Regulation & Expression, College of Life Sciences, University of Dundee, Dundee, United Kingdom; Institut für Biologie, FG Mikrobiologie, Universität Kassel, Germany.
Institut für Biologie, FG Mikrobiologie, Universität Kassel, Germany.
PLoS Genet. 2015 Jan 8;11(1):e1004931. doi: 10.1371/journal.pgen.1004931. eCollection 2015 Jan.
Elongator is a conserved protein complex comprising six different polypeptides that has been ascribed a wide range of functions, but which is now known to be required for modification of uridine residues in the wobble position of a subset of tRNAs in yeast, plants, worms and mammals. In previous work, we showed that Elongator's largest subunit (Elp1; also known as Iki3) was phosphorylated and implicated the yeast casein kinase I Hrr25 in Elongator function. Here we report identification of nine in vivo phosphorylation sites within Elp1 and show that four of these, clustered close to the Elp1 C-terminus and adjacent to a region that binds tRNA, are important for Elongator's tRNA modification function. Hrr25 protein kinase directly modifies Elp1 on two sites (Ser-1198 and Ser-1202) and through analyzing non-phosphorylatable (alanine) and acidic, phosphomimic substitutions at Ser-1198, Ser-1202 and Ser-1209, we provide evidence that phosphorylation plays a positive role in the tRNA modification function of Elongator and may regulate the interaction of Elongator both with its accessory protein Kti12 and with Hrr25 kinase.
延伸因子是一种保守的蛋白质复合物，由六种不同的多肽组成，其功能多样，但现在已知它是酵母、植物、线虫和哺乳动物中一部分转运RNA（tRNA）摆动位置上尿苷残基修饰所必需的。在之前的研究中，我们发现延伸因子的最大亚基（Elp1；也称为Iki3）会发生磷酸化，并认为酵母酪蛋白激酶I Hrr25参与延伸因子的功能。在此，我们报告了在Elp1内鉴定出九个体内磷酸化位点，并表明其中四个位点聚集在Elp1的C末端附近，且毗邻一个结合tRNA的区域，它们对延伸因子的tRNA修饰功能很重要。Hrr25蛋白激酶直接修饰Elp1的两个位点（Ser-1198和Ser-1202），通过分析Ser-1198、Ser-1202和Ser-1209处的非磷酸化（丙氨酸）和酸性磷酸模拟替代，我们提供了证据表明磷酸化在延伸因子的tRNA修饰功能中起积极作用，并且可能调节延伸因子与其辅助蛋白Kti12以及与Hrr25激酶之间的相互作用。
