AtCCR4a and AtCCR4b are Involved in Determining the Poly(A) Length of Granule-bound starch synthase 1 Transcript and Modulating Sucrose and Starch Metabolism in Arabidopsis thaliana
AtCCR4a and AtCCR4b are Involved in Determining the Poly(A) Length of Granule-bound starch synthase 1 Transcript and Modulating Sucrose and Starch Metabolism in Arabidopsis thaliana
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DOI：
10.1093/pcp/pcv012
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发表时间：
2015-05-01
影响因子：
4.9
通讯作者：
Chiba, Yukako
中科院分区：
文献类型：
--
作者：
Suzuki, Yuya;Arae, Toshihiro;Chiba, Yukako
去除poly（A）尾是mRNA降解的第一步和限速步骤，并且显然不仅对于调节mRNA稳定性而且对于许多真核转录物的翻译是有效的步骤。碳分解代谢物阻遏物4（CCR 4）已被确定为酿酒酵母中的主要胞质去腺苷酶。拟南芥同源的酵母CCR 4，AtCCR 4a和AtCCR 4 b，确定了基于序列的分析，然而，它们在植物中的作用和生理意义仍有待阐明。在这项研究中，我们发现AtCCR 4a和AtCCR 4 b定位于细胞质mRNA加工体，这是由许多参与mRNA周转的酶组成的特定颗粒。AtCCR 4a和AtCCR 4 b的双突变体表现出对蔗糖的耐受性，但不耐受葡萄糖。atccr 4a/4 b双突变体幼苗中的蔗糖水平降低，而葡萄糖水平没有观察到差异。此外，atccr 4a/4 b双突变体中直链淀粉水平略有但显著增加。与此观察结果一致，我们发现，转录编码颗粒结合淀粉合成酶1（GBSS 1），这是负责直链淀粉合成，积累到一个更高的水平在atccr 4a/4 b双突变体植物比对照植物。此外，我们发现GBSS 1在双突变体中比对照植物具有更长的poly（A）尾，这表明AtCCR 4a和AtCCR 4 b可以影响与淀粉代谢相关的转录物的poly（A）长度。这些结果表明AtCCR 4a和AtCCR 4 b参与了A. thaliana.
Removing the poly(A) tail is the first and rate-limiting step of mRNA degradation and apparently an effective step not only for modulating mRNA stability but also for translation of many eukaryotic transcripts. Carbon catabolite repressor 4 (CCR4) has been identified as a major cytoplasmic deadenylase in Saccharomyces cerevisiae. The Arabidopsis thaliana homologs of the yeast CCR4, AtCCR4a and AtCCR4b, were identified by sequence-based analysis; however, their role and physiological significance in plants remain to be elucidated. In this study, we revealed that AtCCR4a and AtCCR4b are localized to cytoplasmic mRNA processing bodies, which are specific granules consisting of many enzymes involved in mRNA turnover. Double mutants of AtCCR4a and AtCCR4b exhibited tolerance to sucrose application but not to glucose. The levels of sucrose in the seedlings of the atccr4a/4b double mutants were reduced, whereas no difference was observed in glucose levels. Further, amylose levels were slightly but significantly increased in the atccr4a/4b double mutants. Consistent with this observation, we found that the transcript encoding granule-bound starch synthase 1 (GBSS1), which is responsible for amylose synthesis, is accumulated to a higher level in the atccr4a/4b double mutant plants than in the control plants. Moreover, we revealed that GBSS1 has a longer poly(A) tail in the double mutant than in the control plant, suggesting that AtCCR4a and AtCCR4b can influence the poly(A) length of transcripts related to starch metabolism. Our results collectively suggested that AtCCR4a and AtCCR4b are involved in sucrose and starch metabolism in A. thaliana.