Arabidopsis LEAFY COTYLEDON1 represents a functionally specialized subunit of the CCAAT binding transcription factor
Arabidopsis LEAFY COTYLEDON1 represents a functionally specialized subunit of the CCAAT binding transcription factor
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DOI：
10.1073/pnas.0437909100
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发表时间：
2003-02-18
影响因子：
11.1
通讯作者：
Harada, JJ
中科院分区：
文献类型：
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作者：
Lee, HS;Fischer, RL;Harada, JJ
LEAFY COTYLEDON 1（LEC 1）是拟南芥胚胎发生的许多方面所需的中心调节因子，并且当其异位表达时足以诱导营养细胞中的胚胎发育。我们先前发现，LEC 1编码的CCAAT结合因子的HAP 3亚基和10个拟南芥HAP 3（AHAP 3）亚基可以分为两类，LEC 1型和非LEC 1型，基于它们的B结构域内的序列相似性。通过分析嵌合HAP 3亚基的能力，含有不同的组合结构域从LEC 1和非LEC 1型AHAP 3亚基，以抑制遗传学的LEC 1突变，我们表明，B结构域的LEC 1是必要的和足够的范围内的蛋白质在胚胎发生中的活动。此外，我们确定了一个氨基酸残基，天冬氨酸-55，具体的LEC 1型B域，所需的LEC 1活性在胚胎发生和足以赋予部分LEC 1活性的非LEC 1型B域。基于HAP 3 B结构域和组蛋白折叠基序之间的结构相似性，我们讨论了Asp-55残基如何在功能上区分LEC 1和非LEC 1型AHAP 3亚基。
LEAFY COTYLEDON1 (LEC1) is a central regulator that is required for many aspects of Arabidopsis embryogenesis and sufficient to induce embryo development in vegetative cells when expressed ectopically. We previously showed that LEC1 encodes an HAP3 subunit of the CCAAT binding factor and that the 10 Arabidopsis HAP3 (AHAP3) subunits can be divided into two classes, the LEC1-type and the non-LEC1-type, based on sequence similarity within their B domains. By analyzing the ability of chimeric HAP3 subunits containing different combinations of domains from LEC1 and a non-LEC1-type AHAP3 subunit to suppress genetically the lec1 mutation, we show that the B domain of LEC1 is necessary and sufficient within the context of the protein for its activity in embryogenesis. Moreover, we identify one amino acid residue, Asp-55, specific to the LEC1-type B domain that is required for LEC1 activity in embryogenesis and sufficient to confer partial LEC1 activity to a non-LEC1-type B domain. Based on structural similarities between the HAP3 B domain and histone fold motif, we discuss how the Asp-55 residue may functionally differentiate LEC1 from the non-LEC1-type AHAP3 subunits.