Identification and analysis of the plant peroxisomal targeting signal 1 receptor NtPEX5
Identification and analysis of the plant peroxisomal targeting signal 1 receptor NtPEX5
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DOI：
10.1073/pnas.95.22.13336
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发表时间：
1998-10-27
影响因子：
11.1
通讯作者：
Harada, JJ
中科院分区：
文献类型：
--
作者：
Kragler, F;Lametschwandtner, G;Harada, JJ
蛋白质易位到过氧化物酶体中是通过识别存在于基质蛋白最末端 C 末端 (PTS1) 或 N 末端 (PTS2) 的过氧化物酶体靶向信号来实现的。在哺乳动物和酵母中，过氧化物酶体靶向信号受体 Pex5p 识别由 -SKL 或其变体组成的 PTS1。尽管许多植物过氧化物酶体基质蛋白通过 PTSI 途径转运，但对植物中的 PTSI 受体或任何其他过氧化物酶体组装蛋白知之甚少。我们基于该蛋白与酵母双杂交系统中含有PTS1的蛋白质，核苷酸序列分析显示烟草Pex5p含有7个四肽重复序列，并且NtPEX5与其来自人类的同源物比来自酵母的同源物具有更大的序列相似性。 NtPEX5 融合蛋白（由酵母 Pex5p 的 N 端部分和 NtPEX5 的 C 端区域组成）在酿酒酵母 pex5 突变体中的表达恢复了蛋白易位到过氧化物酶体中。这些实验证实了烟草蛋白作为 PTSI 受体的身份，并表明过氧化物酶体易位装置的组件在功能上是保守的。两种杂交检测表明，NtPEX5 与多种 PTS1 变体相互作用，这些变体也与人类 Pex5p 相互作用。有趣的是，其中一些肽的C端残基偏离了已建立的植物PTS1共有序列，我们得出结论，植物和人类Pex5ps之间存在显着的序列和功能相似性。
Protein translocation into peroxisomes takes place via recognition of a peroxisomal targeting signal present at either the extreme C termini (PTS1) or N termini (PTS2) of matrix proteins. In mammals and yeast, the peroxisomal targeting signal receptor, Pex5p, recognizes the PTS1 consisting of -SKL or variants thereof, Although many plant peroxisomal matrix proteins are transported through the PTSI pathway, little is known about the PTSI receptor or any other peroxisome assembly protein from plants, We cloned tobacco (Nicotiana tabacum) cDNAs encoding Pex5p (Nt-PEX5) based on the protein's interaction with a PTS1-containing protein in the yeast two-hybrid system, Nucleotide sequence analysis revealed that the tobacco Pex5p contains seven tetratricopeptide repeats and that NtPEX5 shares greater sequence similarity with its homolog from humans than from yeast. Expression of NtPEX5 fusion proteins, consisting of the N-terminal part of yeast Pex5p and the C-terminal region of NtPEX5, in a Saccharomyces cerevisiae pex5 mutant restored protein translocation into peroxisomes, These experiments confirmed the identity of the tobacco protein as a PTSI receptor and indicated that components of the peroxisomal translocation apparatus are conserved functionally. Two-hybrid assays showed that NtPEX5 interacts with a wide range of PTS1 variants that also interact with the human Pex5p. Interestingly, the C-terminal residues of some of these peptides deviated from the established plant PTS1 consensus sequence, We conclude that there are significant sequence and functional similarities between the plant and human Pex5ps.