Salt tolerance of Arabidopsis thaliana requires maturation of N-glycosylated proteins in the Golgi apparatus
Salt tolerance of Arabidopsis thaliana requires maturation of N-glycosylated proteins in the Golgi apparatus
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DOI：
10.1073/pnas.0800237105
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发表时间：
2008-04-15
影响因子：
11.1
通讯作者：
Koiwa, Hisashi
中科院分区：
文献类型：
--
作者：
Kang, Jae Sook;Frank, Julia;Koiwa, Hisashi
蛋白质N-糖基化在内质网（ER）和高尔基体是一个重要的过程，在真核细胞。虽然ER中的N-糖基化途径已被证明可以调节植物中的蛋白质质量控制、耐盐性和纤维素生物合成，但没有生物学作用与高尔基体中发生的N-聚糖修饰功能相关。在此，我们提供的证据表明，在N-聚糖成熟缺陷的突变体，如复合聚糖1（cgl 1），比野生型更盐敏感。盐胁迫引起生长抑制，根尖形态异常，胼胝质积累cgl 1，这也观察到在ER寡糖基转移酶突变体，星形孢菌素和温度敏感3a（stt 3a）。与stt 3a不同，cgl 1不会引起未折叠蛋白反应的组成性激活。相反，纤维素生物合成所必需的质膜糖蛋白KORIGAN 1/RADIOLLY SWOLLEN 2（KOR 1/RSW 2）的异常修饰发生在cgl 1和stt 3a中。遗传分析确定了rsw 2，stt 3a和cgl 1突变之间的特定相互作用，表明KOR 1/RSW 2蛋白的功能取决于复杂的N-聚糖。此外，纤维素缺乏的rsw 1 -1和rsw 2 -1植物也是盐敏感的。这些结果表明，植物蛋白N-糖基化功能超出ER中的蛋白质折叠，并且是盐胁迫下足够的细胞壁形成所必需的。
Protein N-glycosylation in the endoplasmic reticulum (ER) and in the Golgi apparatus is an essential process in eukaryotic cells. Although the N-glycosylation pathway in the ER has been shown to regulate protein quality control, salt tolerance, and cellulose biosynthesis in plants, no biological roles have been linked functionally to N-glycan modifications that occur in the Golgi apparatus. Herein, we provide evidence that mutants defective in N-glycan maturation, such as complex glycan 1 (cgl1), are more salt-sensitive than wild type. Salt stress caused growth inhibition, aberrant root-tip morphology, and callose accumulation in cgl1, which were also observed in an ER oligosaccharyltransferase mutant, staurosporin and temperature sensitive 3a (stt3a). Unlike stt3a, cgl1 did not cause constitutive activation of the unfolded protein response. Instead, aberrant modification of the plasma membrane glycoprotein KORRIGAN 1/RADIALLY SWOLLEN 2 (KOR1/RSW2) that is necessary for cellulose biosynthesis occurred in cgl1 and stt3a. Genetic analyses identified specific interactions among rsw2, stt3a, and cgl1 mutations, indicating that the function of KOR1/RSW2 protein depends on complex N-glycans. Furthermore, cellulose deficient rsw1-1 and rsw2-1 plants were also salt-sensitive. These results establish that plant protein N-glycosylation functions beyond protein folding in the ER and is necessary for sufficient cell-wall formation under salt stress.