DOI:http://dx.doi.org/10.1016/j.cell.2016.08.029
今天我們來繼續正文部分,無特殊情況的話每晚八點更新吧。
本篇文獻翻譯還參考了中國水稻研究所倪建平老師發表在《中國稻米》雜誌上的對朱健康院士綜述「Abiotic Stress Signaling and Responses in Plants」的譯文。
ER Stress
內質網脅迫
Both biotic and abiotic stress can cause protein misfolding or the accumulation of unfolded proteins, which is sensed as ER stress by specific sensor proteins in the ER membrane.
生物和非生物脅迫都會引起蛋白質錯誤摺疊或未摺疊蛋白質的積累,這能被內質網膜上由特定的感受蛋白所感知並產生內質網脅迫。
This sensing leads to the expression of genes encoding chaperones and other proteins important for enhancing protein folding capacity, ER-associated degradation (ERAD), or protein translation suppression to reduce the amount of synthesized proteins loaded to ER via the PKR-like ER eIF2a kinase.
protein folding capacity 蛋白摺疊能力
degradation 降解
protein translation 蛋白翻譯
suppression 抑制
synthesized proteins 合成蛋白
loaded 向...裝載,加載到(loading...)
via 通過
PKR-like 類PKR(蛋白激酶R)的 蛋白激酶R是一種先天免疫因子
通過蛋白激酶R樣內質網激酶elF2a,對內質網脅迫的感知會導致一些編碼分子伴侶以及與增強蛋白摺疊能力、調控內質網相關降解(ERAD)或抑制蛋白質翻譯相關基因的表達,從而降低加載到內質網上的新合成蛋白質的總量。
These changes help restore ER homeostasis, i.e., the equilibrium between protein-folding demands and folding capacity, and are known as the unfolded protein response (UPR), a conserved stress response in eukaryotes.
i.e. 即
equilibrium 平衡
demands 需求
unfolded protein response 未摺疊蛋白反應
conserved 保守的
eukaryotes 真核生物,真核細胞
這些變化幫助恢復內質網的穩態,即蛋白質摺疊的需求和摺疊能力之間的平衡,這被稱為未摺疊蛋白反應(UPR)——真核生物體內一種保守的脅迫反應。
Two main types of sensors of ER stress have been identified in plants:
ER membrane-associated transcription factors and an RNA-splicing factor.
RNA-splicing factor RNA剪接因子
植物中兩類主要的內質網脅迫受體已被確定:一種內質網膜相關的轉錄因子和一種RNA剪接因子。
The basic leucine zipper bZIP28 may sense heat and other ER stress agents through its interaction with the chaperone protein BIP (binding immunoglobulin protein) in the ER.
leucine 亮氨酸
zipper 拉鏈(結構)
binding immunoglobulin protein 結合免疫球蛋白
在內質網中,最基本的亮氨酸拉鏈結構bZIP28可能通過與分子伴侶蛋白 BIP(bindingimmunoglobulin protein)互作來感知熱信號及其他內質網脅迫信號。
Unfolded or misfolded proteins accumulate under stress, and these proteins can interact with BIP, which releases bZIP28 for transport to the Golgi, where it is cleaved. Its cytosolic portion then relocates to the nucleus to activate the expression of stress-response genes to restore ER homeostasis.
Golgi 高爾基體
cleaved 裂解
cytosolic portion 胞質部分
relocate 重新定位
未摺疊或錯誤摺疊的蛋白在脅迫下積累,並與BIP相互作用,從而使bZIP28 (從與 BIP 的結合狀態)被釋放出來並轉運向高爾基體,在高爾基體中bZIP28被降解。其(bZIP28)胞質部分則重新定位到細胞核,激活脅迫相關基因的表達並恢復內質網穩態。
bZIP28 may also sense other changes that promote its release from BIP, including alterations in energy charge levels and redox status or interactions between BIP and the DNAJ domain-containing protein chaperone.
alterations 改變
redox status 氧化還原狀態
domain-containing 結構域
DnaJ蛋白是一類很大的蛋白家族,因含有保守的DnaJ結構域而得名。一般作為分子伴侶蛋白。
bZIP28也可以感知能量水平和氧化還原狀態的改變或與BIP以及包含DNAJ 結構域的分子伴侶的相互作用,促使其從與BIP的結合態中釋放。
bZIP17 can be activated by salt stress in a similar manner. In addition, several ER- or plasma-membrane-associated NAC transcription factors can be activated by ER stress and contribute to UPR.
several 幾個,一些
NAC轉錄因子是植物特有的一類轉錄因子,參與植物生長發育等多個過程,能不同程度地提高植物抵抗生物和非生物脅迫的能力。
鹽脅迫也以類似的方式激活bZIP17。此外,一些內質網或者質膜相關的NAC 轉錄因子可以被 ER 脅迫激活並參與 UPR(未摺疊蛋白反應)。
The second type of ER stress sensor in plants is IRE1, a splicing factor conserved from yeast to metazoans.
metazoans 後生動物
後生動物(Metazoa)是除原生動物外所有其他動物的總稱(後生動物亞界)。動物界除原生動物門以外的所有多細胞動物門類的總稱。
植物第二種類型的內質網脅迫感受器是IRE1,一種從酵母到後生動物皆保守的剪接因子。
Presumably, plant IRE1 proteins bind to unfolded proteins and sense ER stress in a manner similar to that of their yeast homolog.
Presumably 據推測
據推測,植物IRE1蛋白質以類似酵母中同源蛋白的方式結合未摺疊蛋白並感知內質網脅迫。
Activated IRE1 in Arabidopsis recognizes and splices bZIP60 mRNA and perhaps other target mRNAs.
擬南芥中激活的IRE1蛋白識別並剪接bZIP60和其他靶mRNAs。
The splicing of bZIP60 mRNA by IRE1 results in a bZIP60 variant that can enter the nucleus to activate UPR genes.
variant 變體
IRE1對bZIP60和mRNA的剪接的結果是產生一個bZIP60 變體,從而進入細胞核激活UPR 基因的表達。
刷上去看看英文原文再複習一遍看能看還能看懂多少。