Mutation in the catalytic subunit of DNA polymerase α influences transcriptional gene silencing and homologous recombination in Arabidopsis
Mutation in the catalytic subunit of DNA polymerase α influences transcriptional gene silencing and homologous recombination in Arabidopsis
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DOI：
10.1111/j.1365-313x.2009.04026.x
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发表时间：
2010-01-01
期刊：
影响因子：
7.2
通讯作者：
Gong, Zhizhong
中科院分区：
文献类型：
--
作者：
Liu, Jun;Ren, Xiaozhi;Gong, Zhizhong
REPRESSOR OF SILENCING 1 (ROS1) 编码一种 DNA 去甲基化酶，可主动去除 DNA 甲基化。 ROS1 突变导致 T-DNA 基因座转录基因沉默，该基因座包含两个基因：RD29A-LUC 和 35S-NPTII，最初在 C24 野生型中表达。这些单位具有不同的沉默调节机制：前一种机制依赖于小干扰RNA（siRNA）指导的DNA甲基化，但后者则不然。我们通过使用沉默的35S-NPTII作为选择标记基因筛选ros1突变体的抑制子来研究后一种基因沉默机制。 pol alpha/incurvata2 (icu2) 基因被分离为 ros1 抑制子之一，因为它的突变导致沉默的 35S-NPTII 基因重新激活。 POL α/ICU2 编码 DNA 聚合酶 α 的催化亚基。 POL α/ICU2 的突变不会影响 DNA 甲基化，但会减少 35S 启动子中的组蛋白 H3 Lys9 二甲基化 (H3K9me2) 修饰。 pol α 突变还影响茎尖分生组织的发育，并通过 G2/M 标记基因 CycB1;1:GUS 的高表达延迟 G2/M 期。此外，pol α/icu2 突变体中的同源重组频率高于 C24 野生型。我们的结果表明 DNA 聚合酶 α 参与介导拟南芥中的表观遗传状态和 DNA 同源重组。
REPRESSOR OF SILENCING 1 (ROS1) encodes a DNA demethylase that actively removes DNA methylation. Mutation in ROS1 leads to transcriptional gene silencing of a T-DNA locus that contains two genes, RD29A-LUC and 35S-NPTII, originally expressed in the C24 wild type. These units have different silencing regulation mechanisms: the former mechanism is dependent on small interfering RNA (siRNA)-directed DNA methylation, but the latter is not. We studied the latter gene silencing mechanism by screening the suppressors of the ros1 mutant using the silenced 35S-NPTII as a selection marker gene. The pol alpha/incurvata2 (icu2) gene was isolated as one ros1 suppressor because its mutation leads to the reactivation of the silenced 35S-NPTII gene. POL alpha/ICU2 encodes a catalytic subunit of DNA polymerase alpha. Mutation of POL alpha/ICU2 did not affect DNA methylation, but reduced histone H3 Lys9 dimethylation (H3K9me2) modification in the 35S promoter. The pol alpha mutation also influences the development of the shoot apical meristem, and delays the G2/M phase with high expression of a G2/M marker gene CycB1;1:GUS. Furthermore, the frequency of homologous recombination is greater in the pol alpha/icu2 mutant than in the C24 wild type. Our results suggest that DNA polymerase alpha is involved in mediating epigenetic states and in DNA homologous recombination in Arabidopsis.