Field Sterling, Conner William Craig, Roberts Daniel M
Department of Biochemistry & Cellular and Molecular Biology, The University of Tennessee, Knoxville, TN, United States.
Front Plant Sci. 2021 Sep 8;12:722940. doi: 10.3389/fpls.2021.722940. eCollection 2021.
During the energy crisis associated with submergence stress, plants restrict mRNA translation and rapidly accumulate stress granules that act as storage hubs for arrested mRNA complexes. One of the proteins associated with hypoxia-induced stress granules in is the calcium-sensor protein CALMODULIN-LIKE 38 (CML38). Here, we show that SUPPRESSOR OF GENE SILENCING 3 (SGS3) is a CML38-binding protein, and that SGS3 and CML38 co-localize within hypoxia-induced RNA stress granule-like structures. Hypoxia-induced SGS3 granules are subject to turnover by autophagy, and this requires both CML38 as well as the AAA-ATPase CELL DIVISION CYCLE 48A (CDC48A). CML38 also interacts directly with CDC48A, and CML38 recruits CDC48A to CML38 granules in planta. Together, this work demonstrates that SGS3 associates with stress granule-like structures during hypoxia stress that are subject to degradation by CML38 and CDC48-dependent autophagy. Further, the work identifies direct regulatory targets for the hypoxia calcium-sensor CML38, and suggest that CML38 association with stress granules and associated regulation of autophagy may be part of the RNA regulatory program during hypoxia stress.
在与淹水胁迫相关的能量危机期间，植物会限制mRNA翻译并迅速积累应激颗粒，这些应激颗粒充当停滞的mRNA复合物的储存中心。与缺氧诱导的应激颗粒相关的一种蛋白质是钙传感器蛋白类钙调蛋白38（CML38）。在此，我们表明基因沉默抑制因子3（SGS3）是一种CML38结合蛋白，并且SGS3和CML38在缺氧诱导的RNA应激颗粒样结构中共定位。缺氧诱导的SGS3颗粒会通过自噬进行周转，这需要CML38以及AAA-ATP酶细胞分裂周期48A（CDC48A）。CML38还直接与CDC48A相互作用，并且CML38在植物中将CDC48A招募到CML38颗粒中。总之，这项工作表明SGS3在缺氧胁迫期间与应激颗粒样结构相关联，这些结构会被CML38和依赖于CDC48的自噬降解。此外，这项工作确定了缺氧钙传感器CML38的直接调控靶点，并表明CML38与应激颗粒的关联以及自噬的相关调控可能是缺氧胁迫期间RNA调控程序的一部分。
