The N-terminal portion of mature aldehyde dehydrogenase affects protein folding and assembly.
The N-terminal portion of mature aldehyde dehydrogenase affects protein folding and assembly.
复制标题
成熟乙醛脱氢酶的 N 末端部分影响蛋白质折叠和组装。
DOI：
10.1110/ps.5301
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Weiner,H
中科院分区：
文献类型：
--
作者：
Zhou,J;Weiner,H
人肝细胞质醛脱氢酶（ALDH1）和线粒体醛脱氢酶（ALDH2）都在细胞核中编码，在细胞质中合成。ALDH1必须在细胞质中折叠，但ALDH2首先作为前体合成，并且在进入线粒体时必须保持未折叠。除了前21个残基（14%）外，两种成熟形式在蛋白质序列水平上具有很高的一致性（68%）；发现它们的三级结构基本相同。ALDH1在体外折叠速度比ALDH2快，可以组装成四聚体，而ALDH2仍然是单体。采用导入法研究ALDH1和ALDH2的折叠状态。pALDH1是通过将前体ALDH2的前体序列与ALDH1的N端融合而成。与前体ALDH2相比，其进口量减少了约10倍。成熟部分N -末端21残基的交换改变了前体ALDH1和前体ALDH2的输入、折叠和组装。与亲本前体ALDH1相比，更多的嵌合ALDH1前体被导入线粒体。嵌合ALDH1前体的对应物嵌合ALDH2前体的进口量比其母体前体ALDH2减少。成熟的ALDH1对尿素变性比ALDH2更稳定。尿素展开能促进前体ALDH1和嵌合前体的导入，但不能促进前体ALDH2的导入，这与ALDH1和嵌合ALDH2比ALDH2更稳定是一致的。成熟蛋白的N端片段，而不是前序，对前体的折叠、组装和稳定性起主要作用，并可能在折叠和前体转运到线粒体中起作用。
Human liver cytosolic (ALDH1) and mitochondrial (ALDH2) aldehyde dehydrogenases are both encoded in the nucleus and synthesized in the cytosol. ALDH1 must fold in the cytosol, but ALDH2 is first synthesized as a precursor and must remain unfolded during import into mitochondria. The two mature forms share high identity (68%) at the protein sequence level except for the first 21 residues (14%); their tertiary structures were found to be essentially identical. ALDH1 folded faster in vitro than ALDH2 and could assemble to tetramers while ALDH2 remained as monomers. Import assay was used as a tool to study the folding status of ALDH1 and ALDH2. pALDH1 was made by fusing the presequence of precursor ALDH2 to the N‐terminal end of ALDH1. Its import was reduced about 10‐fold compared to the precursor ALDH2. The exchange of the N‐terminal 21 residues from the mature portion altered import, folding, and assembly of precursor ALDH1 and precursor ALDH2. More of chimeric ALDH1 precursor was imported into mitochondria compared to its parent precursor ALDH1. The import of chimeric ALDH2 precursor, the counterpart of chimeric ALDH1 precursor, was reduced compared to its parent precursor ALDH2. Mature ALDH1 proved to be more stable against urea denaturation than ALDH2. Urea unfolding improved the import of precursor ALDH1 and the chimeric precursors but not precursor ALDH2, consistent with ALDH1 and the chimeric ALDHs being more stable than ALDH2. The N‐terminal segment of the mature protein, and not the presequence, makes a major contribution to the folding, assembly, and stability of the precursor and may play a role in folding and hence the translocation of the precursor into mitochondria.