Identification of Two Pentatricopeptide Repeat Genes Required for RNA Editing and Zinc Binding by C-terminal Cytidine Deaminase-like Domains
Identification of Two Pentatricopeptide Repeat Genes Required for RNA Editing and Zinc Binding by C-terminal Cytidine Deaminase-like Domains
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DOI：
10.1074/jbc.m113.485755
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发表时间：
2013-12-20
影响因子：
4.8
通讯作者：
Mulligan, R. Michael
中科院分区：
文献类型：
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作者：
Hayes, Michael L.;Giang, Karolyn;Mulligan, R. Michael
背景：许多五肽重复序列（PPR）蛋白是RNA位点特异性因子，包括C-末端DYW脱氨酶结构域。结果：编辑单个位点需要ELI 1和DOT 4。DYW脱氨酶结构域结合两个锌原子。结论：PLS型PPR蛋白C端与胞苷脱氨酶具有相同的分子特征。重要性：本研究首次证明了DYW脱氨酶结构域与锌结合，许多植物细胞器基因组表达的转录本通过C-to-U RNA编辑进行修饰。核编码的五肽重复序列（PPR）蛋白是RNA编辑机制中RNA结合特异性决定簇。生物信息学分析表明，大多数拟南芥PPR蛋白质的RNA编辑事件所必需的包括一个C-末端部分，该部分与脱氨酶的超家族共享结构特征。DYW脱氨酶结构域包括与胞苷脱氨酶共享特征的高度保守的锌结合基序。拟南芥PPR基因ELI 1和DOT 4都具有DYW脱氨酶结构域，并且是叶绿体中单个RNA编辑事件所需的。ELI 1 DYW脱氨酶结构域在大肠杆菌中表达为重组蛋白，并且显示每个多肽结合两个锌原子。因此，DYW脱氨酶结构域结合锌金属离子，如胞苷脱氨酶所预期的，并且可能是编辑复合物的催化组分。遗传互补实验表明，ELI 1的大部分DYW脱氨酶结构域可以被消除，但截短的基因保留了在突变体植物中恢复编辑位点转换的能力。这些结果表明，催化活性可以由编辑体的未表征的蛋白质反式提供。
Background: Many pentatricopeptide repeat (PPR) proteins are RNA site specificity factors and include C-terminal DYW deaminase domains. Results: ELI1 and DOT4 are required for editing single sites. The DYW deaminase domain binds two zinc atoms. Conclusion: The C terminus of PLS-type PPR proteins shares molecular characteristics with cytidine deaminase. Significance: This study provides the first evidence that DYW deaminase domains bind zinc.Many transcripts expressed from plant organelle genomes are modified by C-to-U RNA editing. Nuclear encoded pentatricopeptide repeat (PPR) proteins are required as RNA binding specificity determinants in the RNA editing mechanism. Bioinformatic analysis has shown that most of the Arabidopsis PPR proteins necessary for RNA editing events include a C-terminal portion that shares structural characteristics with a superfamily of deaminases. The DYW deaminase domain includes a highly conserved zinc binding motif that shares characteristics with cytidine deaminases. The Arabidopsis PPR genes, ELI1 and DOT4, both have DYW deaminase domains and are required for single RNA editing events in chloroplasts. The ELI1 DYW deaminase domain was expressed as a recombinant protein in Escherichia coli and was shown to bind two zinc atoms per polypeptide. Thus, the DYW deaminase domain binds a zinc metal ion, as expected for a cytidine deaminase, and is potentially the catalytic component of an editing complex. Genetic complementation experiments demonstrate that large portions of the DYW deaminase domain of ELI1 may be eliminated, but the truncated genes retain the ability to restore editing site conversion in a mutant plant. These results suggest that the catalytic activity can be supplied in trans by uncharacterized protein(s) of the editosome.