APUM23, a nucleolar Puf domain protein, is involved in pre-ribosomal RNA processing and normal growth patterning in Arabidopsis
APUM23, a nucleolar Puf domain protein, is involved in pre-ribosomal RNA processing and normal growth patterning in Arabidopsis
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DOI：
10.1111/j.1365-313x.2010.04393.x
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发表时间：
2010-12-01
期刊：
影响因子：
7.2
通讯作者：
Choi, Sang-Bong
中科院分区：
文献类型：
--
作者：
Abbasi, Nazia;Kim, Ho Bang;Choi, Sang-Bong
p> Pumilio是一种含有连续重复Puf结构域的rna结合蛋白，已知在非植物物种的早期胚胎发生和极化细胞中抑制翻译活性。尽管Pumilio蛋白已在许多真核生物中被鉴定，但它们在植物中的作用尚不清楚。在本研究中，我们鉴定了拟南芥编码基因APUM23。APUM23是组成性表达的，在代谢活跃的组织中表达水平较高，并且在葡萄糖或蔗糖存在时其表达上调。T-DNA插入突变体apum23-1和apum23-2表现出生长缓慢，叶片呈锯齿状和卷曲状，脉状模式异常，栅栏薄壁细胞组织扭曲，这种表型使人想起核蛋白和核糖体蛋白基因突变。细胞内定位研究表明APUM23主要定位于核仁。基于这种定位，研究了rRNA的加工过程。在apum23中，35S pre-rRNA和未加工的18S和5.8S poly(A) rRNA在不影响成熟rnas稳态水平的情况下积累，表明apum23参与了35S pre-rRNA和rRNA成熟副产物的加工和/或降解。apum23突变体显示18S rRNA与生物发生相关的U3和U14小核仁rna （snoRNAs）和核仁内积累的rna水平增加。我们的数据表明APUM23通过rRNA加工在植物发育中起重要作用。
P>Pumilio, an RNA-binding protein that contains tandemly repeated Puf domains, is known to repress translational activity in early embryogenesis and polarized cells of non-plant species. Although Pumilio proteins have been characterized in many eukaryotes, their role in plants is unknown. In the present study, we characterized an Arabidopsis Pumilio-encoding gene, APUM23. APUM23 is constitutively expressed, with higher levels in metabolically active tissues, and its expression is up-regulated in the presence of either glucose or sucrose. The T-DNA insertion mutants apum23-1 and apum23-2 showed slow growth, with serrated and scrunched leaves, an abnormal venation pattern, and distorted organization of the palisade parenchyma cells - a phenotype that is reminiscent of nucleolin and ribosomal protein gene mutants. Intracellular localization studies indicate that APUM23 predominantly localizes to the nucleolus. Based on this localization, rRNA processing was examined. In apum23, 35S pre-rRNA, and unprocessed 18S and 5.8S poly(A) rRNAs, accumulated without affecting the steady-state levels of mature rRNAs, indicating that APUM23 is involved in the processing and/or degradation of 35S pre-rRNA and rRNA maturation by-products. The apum23 mutant showed increased levels of 18S rRNA biogenesis-related U3 and U14 small nucleolar RNAs (snoRNAs) and accumulated RNAs within the nucleolus. Our data suggest that APUM23 plays an important role in plant development via rRNA processing.