Lrg1p is a Rho1 GTPase-activating protein required for efficient cell fusion in yeast
Lrg1p is a Rho1 GTPase-activating protein required for efficient cell fusion in yeast
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DOI：
10.1534/genetics.104.028027
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发表时间：
2004-10-01
期刊：
影响因子：
3.3
通讯作者：
Rose, MD
中科院分区：
文献类型：
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作者：
Fitch, PG;Gammie, AE;Rose, MD
为了鉴定酿酒酵母中的其他细胞融合基因，我们对fus2Delta进行了高拷贝抑制筛选。较高剂量的BEM1、LRG1和FUS1基因部分抑制了fus2Delta细胞融合缺陷。be1和FUS1是许多细胞融合缺陷突变的高拷贝抑制因子，而LRG1仅抑制fus2Delta和rus161Delta。Lrg1p含有一个Rho-GAP同源区。LRG1的完全缺失，以及Rho-GAP编码区的缺失，导致细胞融合率和二倍体形成率与Jas2Delta相比下降。此外，lrr1delta与其他细胞融合突变结合会导致更严重的交配缺陷。与参与细胞融合一致，Lrg1p定位于交配突起的尖端。Lrg1p-GAP结构域强烈特异性刺激Rho1p的GTPase活性，Rho1p是体外β(1-3)-葡聚糖合成酶的调节因子。β(1-3)-葡聚糖沉积在lrg1Delta菌株中增加，在fus2Delta菌株中错定位到交配突起的尖端。高拷贝LRG1抑制了fus2Delta菌株中P（1-3）葡聚糖的错定位。我们得出结论，Lrg1p是参与细胞融合的Rho1pGAP，并推测其作用是局部抑制细胞壁合成，以帮助交配细胞的质膜紧密结合。
To identify additional cell fusion genes in Saccharomyces cerevisiae, we performed a high-copy suppressor screen of fus2Delta. Higher dosage of three genes, BEM1, LRG1, and FUS1, partially suppressed the fus2Delta cell fusion defect. BEM1 and FUS1 were high-copy suppressors of many cell-fusion-defective mutations, whereas LRG1 suppressed only fus2Delta and rus161Delta. Lrg1p contains a Rho-GAP homologous region. Complete deletion of LRG1, as well as deletion of the Rho-GAP coding region, caused decreased rates of cell fusion and diploid formation comparable to that of Jas2Delta. Furthermore, lrg1Delta caused a more severe mating defect in combination with other cell fusion mutations. Consistent with an involvement in cell fusion, Lrg1p localized to the tip of the mating projection. Lrg1p-GAP domain strongly and specifically stimulated the GTPase activity of Rho1p, a regulator of beta(1-3)-glucan synthase in vitro. beta(1-3)-glucan deposition was increased in lrg1Delta strains and mislocalized to the tip of the mating projection in fus2Delta strains. High-copy LRG1 suppressed the mislocalization of P(1-3) glucan in fus2Delta strains. We conclude that Lrg1p is a Rho1pGAP involved in cell fusion and speculate that it acts to locally inhibit cell wall synthesis to aid in the close apposition of the plasma membranes of mating cells.