Reindl Michèle, Stock Janpeter, Hussnaetter Kai P, Genc Aycin, Brachmann Andreas, Schipper Kerstin
Institute for Microbiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
Bioeconomy Science Center, Forschungszentrum Jülich, Jülich, Germany.
Front Microbiol. 2020 Jul 7;11:1529. doi: 10.3389/fmicb.2020.01529. eCollection 2020.
Subcellular targeting of proteins is essential to orchestrate cytokinesis in eukaryotic cells. During cell division of , for example, chitinases must be specifically targeted to the fragmentation zone at the site of cell division to degrade remnant chitin and thus separate mother and daughter cells. Chitinase Cts1 is exported to this location via an unconventional secretion pathway putatively operating in a lock-type manner. The underlying mechanism is largely unexplored. Here, we applied a forward genetic screen based on UV mutagenesis to identify components essential for Cts1 export. The screen revealed a novel factor termed Jps1 lacking known protein domains. Deletion of the corresponding gene confirmed its essential role for Cts1 secretion. Localization studies demonstrated that Jps1 colocalizes with Cts1 in the fragmentation zone of dividing yeast cells. While loss of Jps1 leads to exclusion of Cts1 from the fragmentation zone and strongly reduced unconventional secretion, deletion of the chitinase does not disturb Jps1 localization. Yeast-two hybrid experiments indicate that the two proteins might interact. In essence, we identified a novel component of unconventional secretion that functions in the fragmentation zone to enable export of Cts1. We hypothesize that Jps1 acts as an anchoring factor for Cts1.
蛋白质的亚细胞靶向对于真核细胞中协调胞质分裂至关重要。例如，在细胞分裂期间，几丁质酶必须特异性地靶向到细胞分裂部位的破碎区域，以降解残留的几丁质，从而分离母细胞和子细胞。几丁质酶Cts1通过一种推测以锁定方式运作的非常规分泌途径被转运到这个位置。其潜在机制在很大程度上尚未被探索。在这里，我们应用基于紫外线诱变的正向遗传筛选来鉴定Cts1输出所必需的成分。筛选揭示了一个名为Jps1的新因子，它缺乏已知的蛋白质结构域。相应基因的缺失证实了其对Cts1分泌的重要作用。定位研究表明，Jps1与Cts1在分裂酵母细胞的破碎区域共定位。虽然Jps1的缺失导致Cts1被排除在破碎区域之外，并大大减少了非常规分泌，但几丁质酶的缺失并不干扰Jps1的定位。酵母双杂交实验表明这两种蛋白质可能相互作用。实质上，我们鉴定了一种非常规分泌的新成分，它在破碎区域发挥作用，使Cts1能够输出。我们假设Jps1作为Cts1的锚定因子发挥作用。
