Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ, 08854, USA.
Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ, 08901, USA.
Nat Commun. 2022 Jan 10;13(1):7. doi: 10.1038/s41467-021-27748-w.
Cell polarity is a fundamental feature underlying cell morphogenesis and organismal development. In the Arabidopsis stomatal lineage, the polarity protein BASL controls stomatal asymmetric cell division. However, the cellular machinery by which this intrinsic polarity site is established remains unknown. Here, we identify the PRAF/RLD proteins as BASL physical partners and mutating four PRAF members leads to defects in BASL polarization. Members of PRAF proteins are polarized in stomatal lineage cells in a BASL-dependent manner. Developmental defects of the praf mutants phenocopy those of the gnom mutants. GNOM is an activator of the conserved Arf GTPases and plays important roles in membrane trafficking. We further find PRAF physically interacts with GNOM in vitro and in vivo. Thus, we propose that the positive feedback of BASL and PRAF at the plasma membrane and the connected function of PRAF and GNOM in endosomal trafficking establish intrinsic cell polarity in the Arabidopsis stomatal lineage.
细胞极性是细胞形态发生和机体发育的基础特征。在拟南芥气孔谱系中，极性蛋白 BASL 控制着气孔不对称细胞分裂。然而，建立这个内在极性位点的细胞机制尚不清楚。在这里，我们鉴定出 PRAF/RLD 蛋白是 BASL 的物理伴侣，并且突变四个 PRAF 成员会导致 BASL 极化缺陷。PRAF 蛋白成员在 BASL 依赖性的气孔谱系细胞中呈现极化。praf 突变体的发育缺陷与 gnom 突变体的表型相似。GNOM 是保守的 Arf GTPases 的激活因子，在膜运输中发挥重要作用。我们进一步发现 PRAF 在体外和体内与 GNOM 相互作用。因此，我们提出 BASL 和 PRAF 在质膜上的正反馈以及 PRAF 和 GNOM 在胞内体运输中的连接功能在拟南芥气孔谱系中建立了内在的细胞极性。
