Ddp1 Cooperates with Ppx1 to Counter a Stress Response Initiated by Nonvacuolar Polyphosphate.
Ddp1 Cooperates with Ppx1 to Counter a Stress Response Initiated by Nonvacuolar Polyphosphate.
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作者：
在从细菌到哺乳动物物种的各种细胞中，无机磷酸盐储存在称为聚磷酸盐（polyP）的长链中。这些几乎通用的聚合物，长度从3到数千个磷酸基团，与分子功能相关，包括能量稳态，蛋白质折叠和细胞信号传导。在许多细胞类型中，多磷酸盐集中在亚细胞区室或细胞器中。在芽殖酵母酿酒酵母中，通过膜结合的液泡转运蛋白伴侣（VTC）复合物合成聚P与其易位到液泡腔（溶酶体样细胞器）中偶联，在那里它以高浓度储存。相反，细菌多磷酸盐激酶（PPK）的异位表达导致聚磷酸盐在液泡外的毒性积累。在这项研究中，我们使用无标记质谱法来研究这种毒性的机制。我们发现，PPK表达的结果在激活的应激反应介导的Hog 1和Yak 1激酶和Msn 2/Msn 4转录因子，以及蛋白激酶A（PKA）活性的变化。这种反应被Ddp 1和Ppx 1多聚磷酸酶的联合作用抵消，Ddp 1和Ppx 1多聚磷酸酶一起起作用以抵消聚磷积累和下游毒性。相反，先前提出的哺乳动物聚磷酸酶的异位表达在该模型中不影响PPK介导的毒性，这表明这些酶在体内不直接起聚磷酸酶的作用，或者它们需要高等真核生物特有的辅因子。我们的工作提供了深入了解为什么聚P积累溶酶体样细胞器外是有毒的。此外，它还可以作为探索polyP如何在分子水平上影响保守生物过程的资源。
In diverse cells from bacterial to mammalian species, inorganic phosphate is stored in long chains called polyphosphate (polyP). These nearly universal polymers, ranging from three to thousands of phosphate moieties in length, are associated with molecular functions, including energy homeostasis, protein folding, and cell signaling. In many cell types, polyphosphate is concentrated in subcellular compartments or organelles. In the budding yeast Saccharomyces cerevisiae, polyP synthesis by the membrane-bound vacuolar transporter chaperone (VTC) complex is coupled to its translocation into the lumen of the vacuole, a lysosome-like organelle, where it is stored at high concentrations. In contrast, the ectopic expression of the bacterial polyphosphate kinase (PPK) results in the toxic accumulation of polyP outside the vacuole. In this study, we used label-free mass spectrometry to investigate the mechanisms underlying this toxicity. We find that PPK expression results in the activation of a stress response mediated in part by the Hog1 and Yak1 kinases and the Msn2/Msn4 transcription factors as well as by changes in protein kinase A (PKA) activity. This response is countered by the combined action of the Ddp1 and Ppx1 polyphosphatases that function together to counter polyP accumulation and downstream toxicity. In contrast, the ectopic expression of previously proposed mammalian polyphosphatases did not impact PPK-mediated toxicity in this model, suggesting either that these enzymes do not function directly as polyphosphatases in vivo or that they require cofactors unique to higher eukaryotes. Our work provides insight into why polyP accumulation outside lysosome-like organelles is toxic. Furthermore, it serves as a resource for exploring how polyP may impact conserved biological processes at a molecular level.
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影响因子：
4
作者：
Desfougeres, Yann;Neumann, Heinz;Mayer, Andreas
通讯作者：
Mayer, Andreas
影响因子：
11.3
作者：
Conrad M;Schothorst J;Kankipati HN;Van Zeebroeck G;Rubio-Texeira M;Thevelein JM
通讯作者：
Thevelein JM
影响因子：
6.4
作者：
Bentley-DeSousa A;Downey M
通讯作者：
Downey M
DOI：
10.1111/j.1432-1033.1990.tb19376.x
发表时间：
1990-10-24
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
DENISDUPHIL, M;LECAER, JP;CARREY, EA
通讯作者：
CARREY, EA
影响因子：
5.8
作者：
Craig, R;Beavis, RC
通讯作者：
Beavis, RC