Arabidopsis carboxyl-terminal domain phosphatase-like isoforms share common catalytic and interaction domains but have distinct in planta functions
Arabidopsis carboxyl-terminal domain phosphatase-like isoforms share common catalytic and interaction domains but have distinct in planta functions
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DOI：
10.1104/pp.106.084939
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发表时间：
2006-10-01
期刊：
影响因子：
7.4
通讯作者：
Koiwa, Hisashi
中科院分区：
文献类型：
--
作者：
Bang, Wooyoung;Kim, Sewon;Koiwa, Hisashi
拟南芥 (Arabidopsis thaliana) 多基因家族（预计有 20 多个成员）编码植物 C 末端结构域 (CTD) 磷酸酶，该磷酸酶可使 RNA 聚合酶 II C 末端串联七联体重复序列中的 Ser 残基去磷酸化。 CTD 磷酸酶样 (CPL) 亚型 1 和 3 是渗透压和脱落酸 (ABA) 信号传导的调节剂。本文提供的证据表明 CPL3 和 CPL4 是原型 CTD 磷酸酶 FCP1（TFIIF 相互作用 CTD 磷酸酶）的同源物。 CPL3 和 CPL4 包含催化 FCP1 同源性和乳腺癌 1 C 末端 (BRCT) 结构域。重组 CPL3 和 CPL4 与 AtRAP74 相互作用，AtRAP74 是 FCP1 相互作用的 TFIIF 亚基的拟南芥直系同源物。包含 BRCT 结构域的 CPL3 或 CPL4 C 末端片段介导与 AtRAP74 的分子相互作用。与预测的转录调控作用一致，CPL3、CPL4 和 RAP74 的绿色荧光蛋白融合蛋白均定位于细胞核。消除 BRCT 或 FCP1 同源结构域的 cpl3 突变会导致胁迫诱导型 RD29a 启动子的 ABA 过度激活，而 CPL4 的 RNAi 抑制会导致矮化和幼苗生长减少。这些结果表明 CPL3 和 CPL4 是一对旁系同源的通用转录调节因子，具有相似的生化特性，但它们是不同的发育和环境反应所必需的。 CPL4 对于正常植物生长是必需的，因此与真菌和后生动物 FCP1 最为直系同源，而 CPL3 是一种专门促进 ABA 信号转导的亚型。
An Arabidopsis (Arabidopsis thaliana) multigene family (predicted to be more than 20 members) encodes plant C-terminal domain (CTD) phosphatases that dephosphorylate Ser residues in tandem heptad repeat sequences of the RNA polymerase II C terminus. CTD phosphatase-like (CPL) isoforms 1 and 3 are regulators of osmotic stress and abscisic acid (ABA) signaling. Evidence presented herein indicates that CPL3 and CPL4 are homologs of a prototype CTD phosphatase, FCP1 (TFIIF-interacting CTD-phosphatase). CPL3 and CPL4 contain catalytic FCP1 homology and breast cancer 1 C terminus (BRCT) domains. Recombinant CPL3 and CPL4 interact with AtRAP74, an Arabidopsis ortholog of a FCP1-interacting TFIIF subunit. A CPL3 or CPL4 C-terminal fragment that contains the BRCT domain mediates molecular interaction with AtRAP74. Consistent with their predicted roles in transcriptional regulation, green fluorescent protein fusion proteins of CPL3, CPL4, and RAP74 all localize to the nucleus. cpl3 mutations that eliminate the BRCT or FCP1 homology domain cause ABA hyperactivation of the stress-inducible RD29a promoter, whereas RNAi suppression of CPL4 results in dwarfism and reduced seedling growth. These results indicate CPL3 and CPL4 are a paralogous pair of general transcription regulators with similar biochemical properties, but are required for the distinct developmental and environmental responses. CPL4 is necessary for normal plant growth and thus most orthologous to fungal and metazoan FCP1, whereas CPL3 is an isoform that specifically facilitates ABA signaling.