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A mitochondrial prolyl aminopeptidase PAP2 releases N-terminal proline and regulates proline homeostasis during stress response.
The Plant Journal ( IF 7.2 ) Pub Date : 2020-09-13 , DOI: 10.1111/tpj.14987
Abi S Ghifari 1, 2 , Pedro F Teixeira 3 , Beata Kmiec 3 , Adriana Pružinská 1, 2 , Elzbieta Glaser 3 , Monika W Murcha 1, 2
Affiliation  

Most mitochondrial proteins are synthesised in the cytosol and targeted into the organelle via N‐terminal targeting peptides that are cleaved upon import. The free targeting peptide is subsequently processed in a stepwise manner, with single amino acids released as final products. Here, we have characterised a proline‐cleaving aminopeptidase in Arabidopsis thaliana, prolyl aminopeptidase‐2 (PAP2, At3g61540). Activity assays show that PAP2 has a preferred activity to hydrolyse N‐terminal proline. Protein localisation studies revealed that PAP2 is exclusively targeted to mitochondria. Characterisation of pap2 mutants show defective pollen, enhanced dark‐induced senescence and increased susceptibility to abiotic stresses, which are likely attributed to a reduced level of accumulated free proline. Taken together, these results demonstrate the role of PAP2 in proline cleavage from mitochondrial peptides and proline homeostasis, which is required for the development of male gametophyte, tolerance to abiotic stresses, and leaf senescence.

中文翻译:

线粒体脯氨酰氨肽酶PAP2释放N末端脯氨酸,并在应激反应过程中调节脯氨酸稳态。

大多数线粒体蛋白在细胞质中合成,并通过导入时裂解的N端靶向肽靶向细胞器。随后以逐步方式加工游离的靶向肽,释放出单个氨基酸作为最终产物。在这里,我们已经描述了拟南芥中脯氨酸裂解的氨肽酶,脯氨酰氨肽酶-2(PAP2,At3g61540)的特征。活性测定表明,PAP2具有水解N末端脯氨酸的优先活性。蛋白质定位研究表明,PAP2仅针对线粒体。表征PAP2突变体显示出花粉缺陷,黑暗诱导的衰老增强以及对非生物胁迫的敏感性增加,这很可能归因于游离脯氨酸的积累水平降低。综上所述,这些结果证明了PAP2在线粒体肽脯氨酸切割和脯氨酸稳态中的作用,这是雄配子体发育,对非生物胁迫的耐受性和叶片衰老所必需的。
更新日期:2020-09-13
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