Molecular Genetics Department, Centre for Research on Agricultural Genomics CRAG, Campus UAB 08193 Bellaterra, Cerdanyola del Vallès, Barcelona, Spain.
Mol Cell Biochem. 2011 Oct;356(1-2):255-60. doi: 10.1007/s11010-011-0971-6. Epub 2011 Jul 13.
In all eukaryotes, the typical CK2 holoenzyme is an heterotetramer composed of two catalytic (CK2α and CK2α') and two regulatory (CK2β) subunits. One of the distinctive traits of plant CK2 is that they present a greater number of genes encoding for CK2α/β subunits than animals or yeasts, for instance, in Arabidopsis and maize both CK2α/β subunits belong to multigenic families composed by up to four genes. Here, we conducted a genome-wide survey examining 34 different plant genomes in order to investigate if the multigenic property of CK2β genes is a common feature through the entire plant kingdom. Also, at the level of structure, the plant CK2β regulatory subunits present distinctive features as (i) they lack about 20 aminoacids in the C-terminal domain, (ii) they present a specific N-terminal extension of about 90 aminoacids that shares no homology with any previously characterized functional domain, and (iii) the acidic loop region is poorly conserved at the aminoacid level. Since there is no data about CK2β or holoenzyme structure in plants, in this study, we use human CK2β as a template to predict a structure for Zea mays CK2β1 by homology modeling and we discuss about possible structural changes in the acidic loop region that could affect the enzyme regulation.
在所有真核生物中，典型的 CK2 全酶是由两个催化（CK2α 和 CK2α'）和两个调节（CK2β）亚基组成的异四聚体。植物 CK2 的一个显著特征是，它们编码 CK2α/β亚基的基因数量多于动物或酵母，例如，在拟南芥和玉米中，CK2α/β亚基都属于由多达四个基因组成的多基因家族。在这里，我们进行了一次全基因组调查，研究了 34 种不同的植物基因组，以研究 CK2β 基因的多基因特性是否是整个植物界的共同特征。此外，在结构水平上，植物 CK2β 调节亚基具有独特的特征，即（i）它们在 C 末端结构域缺失约 20 个氨基酸，（ii）它们具有约 90 个氨基酸的特定 N 末端延伸，与任何以前表征的功能结构域均无同源性，（iii）酸性环区在氨基酸水平上保守性差。由于植物中没有关于 CK2β 或全酶结构的数据，在本研究中，我们使用人 CK2β 作为模板，通过同源建模预测玉米 CK2β1 的结构，并讨论酸性环区可能影响酶调节的结构变化。
