Arabidopsis thaliana transcriptional co-activators ADA2b and SGF29a are implicated in salt stress responses
Arabidopsis thaliana transcriptional co-activators ADA2b and SGF29a are implicated in salt stress responses
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DOI：
10.1007/s00425-010-1337-0
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发表时间：
2011-04-01
期刊：
影响因子：
4.3
通讯作者：
Vlachonasios, Konstantinos E.
中科院分区：
文献类型：
--
作者：
Kaldis, Athanasios;Tsementzi, Despoina;Vlachonasios, Konstantinos E.
转录共激活剂ADA2b是真核生物中含有gcn5复合物的一个组分。在拟南芥中，ada2b突变体导致多效性发育缺陷和对低温胁迫的反应改变。SGF29最近被鉴定为含gcn5复合物的另一个组分。在拟南芥基因组中，酵母SGF29有两个同源基因，分别为SGF29a和SGF29b。我们假设，在拟南芥中，一个或两个SGF29蛋白可能与ADA2b协同作用，调节非生物胁迫下的基因，我们开始探索SGF29a和ADA2b在盐胁迫反应中的作用。在根生长和种子萌发试验中，sgf29a-1突变体对盐胁迫的抗性比野生型强，而ada2b-1突变体对盐胁迫敏感。sgf29a;Ada2b双突变体表现出与Ada2b -1突变体相似的表型，但盐敏感性降低。与sgf29a-1和野生型植物相比，盐胁迫3 h后，ada2b-1突变体中几个非生物胁迫应答基因的表达降低。在sgf29a-1；Ada2b-1双突变体，盐诱导的基因表达受到类似Ada2b-1的影响。这些结果表明，在盐胁迫下，SGF29a的功能被ADA2b掩盖，SGF29a可能在ADA2b的作用下起辅助作用。在染色质免疫沉淀实验中，与野生型植物相比，ada2b-1突变体中COR6.6、RAB18和RD29b基因启动子和编码区组蛋白H3和H4乙酰化水平降低。综上所述，ADA2b通过维持组蛋白H4和H3的位点特异性乙酰化，积极调节盐诱导的基因表达。
The transcriptional co-activator ADA2b is a component of GCN5-containing complexes in eukaryotes. In Arabidopsis, ada2b mutants result in pleiotropic developmental defects and altered responses to low-temperature stress. SGF29 has recently been identified as another component of GCN5-containing complexes. In the Arabidopsis genome there are two orthologs of yeast SGF29, designated as SGF29a and SGF29b. We hypothesized that, in Arabidopsis, one or both SGF29 proteins may work in concert with ADA2b to regulate genes in response to abiotic stress, and we set out to explore the role of SGF29a and ADA2b in salt stress responses. In root growth and seed germination assays, sgf29a-1 mutants were more resistant to salt stress than their wild-type counterparts, whereas ada2b-1 mutant was hypersensitive. The sgf29a;ada2b double mutant displayed similar phenotypes to ada2b-1 mutant with reduced salt sensitivity. The expression of several abiotic stress-responsive genes was reduced in ada2b-1 mutants after 3 h of salt stress in comparison with sgf29a-1 and wild-type plants. In the sgf29a-1;ada2b-1 double mutant, the salt-induced gene expression was affected similarly to ada2b-1. These results suggest that under salt stress the function of SGF29a was masked by ADA2b and perhaps SGF29a could play an auxiliary role to ADA2b action. In chromatin immunoprecipitation assays, reduced levels of histone H3 and H4 acetylation in the promoter and coding region of COR6.6, RAB18, and RD29b genes were observed in ada2b-1 mutants relative to wild-type plants. In conclusion, ADA2b positively regulates salt-induced gene expression by maintaining the locus-specific acetylation of histones H4 and H3.