The cell wall is essential for cell viability and pathogenesis of fungi. It was previously shown that the exocytosis landmark Sec3 is an effector of the cell wall integrity (CWI) master regulator Rho1 GTPase. However, disruption of the interaction between Sec3 and Rho1 did not inhibit exocytic secretion and cell growth. The physiological role of Sec3 in fungi is unclear. We have examined the growth, cell wall sensitivity, exocyst localization, and exocytic secretion of Sec3-binding deficient rho1 mutants and Rho1-binding deficient sec3 mutants. We found that the Sec3 N-terminal deletion mutant was defective in cell wall integrity. The cells harboring binding mutation between Rho1 and Sec3 N-terminus were sensitive to cell wall antagonists. We also found that the polarized localization of exocyst subunits was disrupted in these mutants. Our study demonstrates that the N-terminus of Sec3 mediates cell wall integrity in yeast. Pathogenic fungi may use similar regulatory mechanisms because components of the exocytic signaling pathways are conserved.

细胞壁对于细胞活力和真菌的发病机理至关重要。先前已表明，胞吐标志物Sec3是细胞壁完整性（CWI）主调节剂Rho1 GTPase的效应子。但是，Sec3和Rho1之间的相互作用的破坏并没有抑制细胞外分泌和细胞生长。Sec3在真菌中的生理作用尚不清楚。我们已经检查了Sec3结合缺陷型rho1突变体和Rho1结合缺陷型sec3的生长，细胞壁敏感性，囊外定位和细胞外分泌。突变体。我们发现Sec3 N端缺失突变体在细胞壁完整性方面存在缺陷。在Rho1和Sec3 N端之间具有结合突变的细胞对细胞壁拮抗剂敏感。我们还发现，在这些突变体中，囊外亚基的极化定位被破坏了。我们的研究表明，Sec3的N端介导了酵母细胞壁的完整性。致病真菌可能使用类似的调节机制，因为胞外信号转导途径的组成是保守的。