N-glycosylation does not affect the catalytic activity of ricin a chain but stimulates cytotoxicity by promoting its transport out of the endoplasmic reticulum.
N-glycosylation does not affect the catalytic activity of ricin a chain but stimulates cytotoxicity by promoting its transport out of the endoplasmic reticulum.
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DOI：
10.1111/j.1600-0854.2012.01404.x
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发表时间：
2012-11
期刊：
影响因子：
--
通讯作者：
Tumer NE
中科院分区：
文献类型：
--
作者：
Yan Q;Li XP;Tumer NE
蓖麻毒素A链（RTA）在α-八叠球菌毒素/蓖麻毒素环逆行运输到胞质溶胶后将其脱嘌呤。RTA参与细胞内转运的结构特征尚不清楚。为了探索这一点，我们将EGFP融合到含有35个残基前导序列的前体（preRTA-EGFP）和成熟RTA（matRTA-EGFP）。两者在S.啤酒。PreRTA-EGFP最初定位于内质网（ER）中，随后被运输到液泡中，而成熟的RTA保留在胞质溶胶中，表明ER定位是液泡运输的先决条件。当RTA中的两个糖基化位点发生突变时，成熟形式是完全活性和毒性的，这表明突变不影响催化活性。然而，非糖基化的preRTA-EGFP具有降低的毒性、脱嘌呤和延迟的空泡转运，表明N-糖基化影响RTA从ER的转运。在C-末端疏水区的点突变限制RTA的ER和消除毒性和脱嘌呤，表明该序列是关键的ER退出。这些结果表明，N-糖基化和C-末端疏水区域通过促进ER输出来刺激RTA的毒性。脱嘌呤的时间与液泡运输的时间相吻合，表明RTA可能在液泡运输过程中进入胞质溶胶。
Ricin A chain (RTA) depurinates the α-sarcin/ricin loop after it undergoes retrograde trafficking to the cytosol. The structural features of RTA involved in intracellular transport are not known. To explore this, we fused EGFP to precursor (preRTA-EGFP), containing a 35-residue leader, and mature RTA (matRTA-EGFP). Both were enzymatically active and toxic in S. cerevisiae. PreRTA-EGFP was localized in the endoplasmic reticulum (ER) initially and was subsequently transported to the vacuole, while mature RTA remained in the cytosol, indicating that ER localization is a prerequisite for vacuole transport. When the two glycosylation sites in RTA were mutated, mature form was fully active and toxic, suggesting that the mutations do not affect catalytic activity. However, nonglycosylated preRTA-EGFP had reduced toxicity, depurination and delayed vacuole transport, indicating that N-glycosylation affects transport of RTA out of the ER. Point mutations in the C-terminal hydrophobic region restricted RTA to the ER and eliminated toxicity and depurination, indicating that this sequence is critical for ER exit. These results demonstrate that N-glycosylation and the C-terminal hydrophobic region stimulate the toxicity of RTA by promoting ER export. The timing of depurination coincided with the timing of vacuole transport, suggesting that RTA may enter the cytosol during vacuole transport.
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影响因子：
3.1
作者：
Li, Xiao-Ping;Baricevic, Marianne;Tumer, Nigun E.
通讯作者：
Tumer, Nigun E.
影响因子：
3.3
作者：
Li, Shuyu;Spooner, Robert A.;Roberts, Lynne M.
通讯作者：
Roberts, Lynne M.
DOI：
10.1002/prot.340100308
发表时间：
1991-01-01
期刊：
PROTEINS-STRUCTURE FUNCTION AND GENETICS
影响因子：
--
作者：
RUTENBER, E;KATZIN, BJ;ROBERTUS, JD
通讯作者：
ROBERTUS, JD
影响因子：
4.8
作者：
Parikh, Bijal A.;Tortora, Andrew;Tumer, Nilgun E.
通讯作者：
Tumer, Nilgun E.
DOI：
10.1111/j.1432-1033.1985.tb08667.x
发表时间：
1985-01-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
LORD, JM
通讯作者：
LORD, JM