A novel abi5 allele reveals the importance of the conserved Ala in the C3 domain for regulation of downstream genes and salt tolerance during germination in Arabidopsis.
A novel abi5 allele reveals the importance of the conserved Ala in the C3 domain for regulation of downstream genes and salt tolerance during germination in Arabidopsis.
复制标题
DOI：
10.4161/psb.23455
复制
发表时间：
2013-03
影响因子：
2.9
通讯作者：
Sakata Y
中科院分区：
文献类型：
--
作者：
Tezuka K;Taji T;Hayashi T;Sakata Y
拟南芥种子发育和萌发过程中ABA信号转导需要ABA INSENSITIVE5 （ABI5）编码的a组bZIP转录因子。除了基本亮氨酸拉链DNA结合域外，A组bZIPs还具有3个n端保守区（C1、C2和C3）和1个c端保守区（C4）。这些保守区域被认为在ABI5功能中发挥作用；然而，除了磷酸化位点外，高度保守的氨基酸的重要性尚不清楚。在这里，我们报道了一个新的abi5隐性等位基因（abi5-9），它编码一个完整的abi5蛋白，在C3结构域有一个氨基酸替换（A214G）。abi5-9植株在萌发过程中表现为ABA不敏感，在含有175 mM NaCl或500 mM甘露醇的培养基上均能萌发。与野生型相比，ABI5 -9型植物的Em1和em6的表达水平非常低，这两个基因编码晚期胚胎发生丰度（LEA）蛋白，并直接被ABI5调控。在酵母中，与ABI5相比，ABI5 -9蛋白与ABI3的相互作用大大降低。这些数据表明，ABI5中的Ala214通过与ABI3的相互作用来促进ABI5的功能。
Abscisic acid (ABA) signal transduction during Arabidopsis seed development and germination requires a Group A bZIP transcription factor encoded by ABA INSENSITIVE5 (ABI5). In addition to the basic leucine zipper DNA binding domain, Group A bZIPs are characterized by three N-terminal conserved regions (C1, C2 and C3) and one C-terminal conserved region (C4). These conserved regions are considered to play roles in ABI5 functions; however, except for the phosphorylation site, the importance of the highly conserved amino acids is unclear. Here, we report a novel abi5 recessive allele (abi5-9) that encodes an intact ABI5 protein with one amino acid substitution (A214G) in the C3 domain. The abi5-9 plants showed ABA insensitivity during germination and could germinate on medium containing 175 mM NaCl or 500 mM mannitol. Em1 and Em6—both encoding late embryogenesis abundant (LEA) proteins and directly targeted by ABI5 regulation—were expressed at very low levels in abi5-9 plants compared with the wild type. In yeast, the abi5-9 protein exhibited greatly reduced interaction with ABI3 compared with ABI5. These data suggest that Ala214 in ABI5 contributes to the function of ABI5 via its interaction with ABI3.