Jung Daehee, Ahn Jihye, Rhee Boram, Kim Jinmi
Department of Microbiology and Molecular Biology, College of Bioscience and Biotechnology, Chungnam National University, Daejeon, 34134, Republic of Korea.
J Microbiol. 2017 May;55(5):373-378. doi: 10.1007/s12275-017-7020-4. Epub 2017 Apr 29.
Dhh1 and Dhh1 homologues (RCK/p54/DDX6) are members of the DEAD-box protein family of RNA helicases. These proteins display conserved sequence motifs for ATPase and RNA binding activities. Dhh1 is a component of the P-bodies (processing bodies) of mRNA granules and functions as an mRNA decapping activator in Saccharomyces cerevisiae. Dhh1 also contributes to gene-specific regulation during yeast mating. The dhh1 deletion mutation results in a significant decrease in the expression of Ste12, a mating-specific transcription factor, showing severe mating defects. Here, we introduced amino-acid substitution mutations in the ATPase and RNA binding domains of Dhh1 and also constructed a deletion of 79 amino acids at the Q/P-rich C-terminal region. The mutations in ATPase A and B motif (K96R, D195A) and C-terminus deletion showed reduced levels of mating efficiency as well as Ste12 protein expression. The Q/P-rich C-terminal region of Dhh1 was dispensable for growth at nonpermissive temperature 37°C but appeared to play an important role in regulating the Ste12 protein expression and mating processes. The P-body accumulation induced by treatment with α-mating factor required ATPase, RNA-binding and the Q/P-rich C-terminal domains of Dhh1.
Dhh1及其同源物（RCK/p54/DDX6）是RNA解旋酶的DEAD-box蛋白家族成员。这些蛋白质展示出用于ATP酶和RNA结合活性的保守序列基序。Dhh1是mRNA颗粒的P小体（加工小体）的一个组成部分，在酿酒酵母中作为mRNA去帽激活剂发挥作用。Dhh1在酵母交配过程中也有助于基因特异性调控。dhh1缺失突变导致交配特异性转录因子Ste12的表达显著降低，表现出严重的交配缺陷。在这里，我们在Dhh1的ATP酶和RNA结合结构域中引入了氨基酸替代突变，并且在富含Q/P的C末端区域构建了一个79个氨基酸的缺失。ATP酶A和B基序（K96R、D195A）中的突变以及C末端缺失显示出交配效率和Ste12蛋白表达水平降低。Dhh1富含Q/P的C末端区域在37°C的非允许温度下对生长是可有可无的，但似乎在调节Ste12蛋白表达和交配过程中发挥重要作用。用α交配因子处理诱导的P小体积聚需要Dhh1的ATP酶、RNA结合和富含Q/P的C末端结构域。
