Stankovic-Valentin Nicolas, Drzewicka Katarzyna, König Cornelia, Schiebel Elmar, Melchior Frauke
Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) Heidelberg University DKFZ - ZMBH Alliance, Heidelberg, Germany.
Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH) Heidelberg University DKFZ - ZMBH Alliance, Heidelberg, Germany
EMBO J. 2016 Jun 15;35(12):1312-29. doi: 10.15252/embj.201593404. Epub 2016 May 12.
To sense and defend against oxidative stress, cells depend on signal transduction cascades involving redox-sensitive proteins. We previously identified SUMO (small ubiquitin-related modifier) enzymes as downstream effectors of reactive oxygen species (ROS). Hydrogen peroxide transiently inactivates SUMO E1 and E2 enzymes by inducing a disulfide bond between their catalytic cysteines. How important their oxidation is in light of many other redox-regulated proteins has however been unclear. To selectively disrupt this redox switch, we identified a catalytically fully active SUMO E2 enzyme variant (Ubc9 D100A) with strongly reduced propensity to maintain a disulfide with the E1 enzyme in vitro and in cells. Replacement of Ubc9 by this variant impairs cell survival both under acute and mild chronic oxidative stresses. Intriguingly, Ubc9 D100A cells fail to maintain activity of the ATM-Chk2 DNA damage response pathway that is induced by hydrogen peroxide. In line with this, these cells are also more sensitive to the ROS-producing chemotherapeutic drugs etoposide/Vp16 and Ara-C. These findings reveal that SUMO E1~E2 oxidation is an essential redox switch in oxidative stress.
为了感知并抵御氧化应激，细胞依赖于涉及氧化还原敏感蛋白的信号转导级联反应。我们之前将SUMO（小泛素相关修饰物）酶鉴定为活性氧（ROS）的下游效应器。过氧化氢通过在其催化半胱氨酸之间诱导形成二硫键，短暂地使SUMO E1和E2酶失活。然而，鉴于许多其他氧化还原调节蛋白，其氧化的重要性尚不清楚。为了选择性地破坏这种氧化还原开关，我们鉴定了一种催化活性完全的SUMO E2酶变体（Ubc9 D100A），其在体外和细胞中与E1酶维持二硫键的倾向大大降低。用这种变体替代Ubc9会损害急性和轻度慢性氧化应激下的细胞存活。有趣的是，Ubc9 D100A细胞无法维持由过氧化氢诱导的ATM-Chk2 DNA损伤反应途径的活性。与此一致的是，这些细胞对产生ROS的化疗药物依托泊苷/Vp16和阿糖胞苷也更敏感。这些发现表明SUMO E1~E2氧化是氧化应激中一个重要的氧化还原开关。
