Plant catalases are important antioxidant enzymes and are indispensable for plant to cope with adverse environmental stresses. However, little is known how catalase activity is regulated especially at an organelle lev...Plant catalases are important antioxidant enzymes and are indispensable for plant to cope with adverse environmental stresses. However, little is known how catalase activity is regulated especially at an organelle level. In this study, we identified that small heat shock protein Hsp17.6Cll （AT5GI2020） in- teracts with and activates catalases in the peroxisome of Arabidopsis thaliana. Although Hsp17.6Cll is classified into the cytosol-located small heat shock protein subfamily, we found that Hsp17.6ClI is located in the peroxisome. Moreover, Hsp17.6ClI contains a novel non-canonical peroxisome targeting signal 1 （PTS1）, QKL, 16 amino acids upstream from the C-terminus. The QKL signal peptide can partially locate GFP to peroxisome, and mutations in the tripeptide lead to the abolishment of this activity. In vitro catalase activity assay and holdase activity assay showed that Hsp17.6ClI increases CAT2 activity and prevents it from thermal aggregation. These results indicate that Hspl7.6ClI is a peroxisome-localized catalase chaperone. Overexpression of HsplK6II conferred enhanced catalase activity and tolerance to abiotic stresses in grabidopsis. Interestingly, overexpression of HspI7.6CII in catalase-deficient mutants, ncal-3 and cat2 cat3, failed to rescue their stress-sensitive phenotypes and catalase activity, suggesting that HsplT.6Cll-mediated stress response is dependent on NCA1 and catalase activity. Overall, we identified a novel peroxisome-located catalase chaperone that is involved in plant abiotic stress resis- tance by activating catalase activity.展开更多
为了探讨热激蛋白在低温锻炼诱导的耐热性形成过程中的保护功能,进一步分析葡萄幼苗对温度逆境产生交叉适应性的细胞学机制,试验以葡萄(Vitis vinifera L. cv. Jingxiu)幼苗为试材,采用胶体金免疫电镜定位技术,定位观察了小分子热激蛋白...为了探讨热激蛋白在低温锻炼诱导的耐热性形成过程中的保护功能,进一步分析葡萄幼苗对温度逆境产生交叉适应性的细胞学机制,试验以葡萄(Vitis vinifera L. cv. Jingxiu)幼苗为试材,采用胶体金免疫电镜定位技术,定位观察了小分子热激蛋白17.6(sHSP17.6)在葡萄叶片中的亚细胞分布情况,结果表明,低温锻炼预处理可增强其在高温胁迫条件下的表达水平,细胞核和叶绿体中代表sHSP17.6的免疫金颗粒密度比相应的对照细胞明显增多,尤其是胁迫处理3 h时。这一结果为sHSP17.6参与低温锻炼诱导的耐热性提供了更直观的细胞学证据。展开更多
基金supported by The Project-sponsored by SRF for ROCS,SEM.(2006)grants from Natural Scientific Foundation of China(30660014)Natural Scientific Foundation of Inner Mongolia(200508010503)~~
基金supported by the National Natural Science Foundation of China (No. 31430012 to Y.G.)the National Basic Research Program of China(No. 2015CB910202 to Y.G.)Foundation for Innovative Research Group of the National Natural Science Foundation of China(No. 31121002)
文摘Plant catalases are important antioxidant enzymes and are indispensable for plant to cope with adverse environmental stresses. However, little is known how catalase activity is regulated especially at an organelle level. In this study, we identified that small heat shock protein Hsp17.6Cll （AT5GI2020） in- teracts with and activates catalases in the peroxisome of Arabidopsis thaliana. Although Hsp17.6Cll is classified into the cytosol-located small heat shock protein subfamily, we found that Hsp17.6ClI is located in the peroxisome. Moreover, Hsp17.6ClI contains a novel non-canonical peroxisome targeting signal 1 （PTS1）, QKL, 16 amino acids upstream from the C-terminus. The QKL signal peptide can partially locate GFP to peroxisome, and mutations in the tripeptide lead to the abolishment of this activity. In vitro catalase activity assay and holdase activity assay showed that Hsp17.6ClI increases CAT2 activity and prevents it from thermal aggregation. These results indicate that Hspl7.6ClI is a peroxisome-localized catalase chaperone. Overexpression of HsplK6II conferred enhanced catalase activity and tolerance to abiotic stresses in grabidopsis. Interestingly, overexpression of HspI7.6CII in catalase-deficient mutants, ncal-3 and cat2 cat3, failed to rescue their stress-sensitive phenotypes and catalase activity, suggesting that HsplT.6Cll-mediated stress response is dependent on NCA1 and catalase activity. Overall, we identified a novel peroxisome-located catalase chaperone that is involved in plant abiotic stress resis- tance by activating catalase activity.
