A Role for the Rap GTPase YlRsr1 in Cellular Morphogenesis and the Involvement of YlRsr1 and the Ras GTPase YlRas2 in Bud Site Selection in the Dimorphic Yeast Yarrowia lipolytica
A Role for the Rap GTPase YlRsr1 in Cellular Morphogenesis and the Involvement of YlRsr1 and the Ras GTPase YlRas2 in Bud Site Selection in the Dimorphic Yeast Yarrowia lipolytica
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Rap GTPase YlRsr1 在细胞形态发生中的作用以及 YlRsr1 和 Ras GTPase YlRas2 在二态性解脂耶氏酵母芽位点选择中的参与
DOI：
10.1128/ec.00342-13
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发表时间：
2014-05-01
期刊：
影响因子：
--
通讯作者：
Gao, Xiang-Dong
中科院分区：
文献类型：
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作者：
Li, Yun-Qing;Li, Min;Gao, Xiang-Dong
解脂耶氏酵母是一种二型酵母，根据生长条件的不同，它可以以卵球形酵母形态生长，也可以以细长的假菌丝或菌丝形态生长。在这里，我们证明了Y.解脂菌（YlRsr 1）在该微生物的细胞形态发生中起重要作用。缺失YlRSR 1的细胞在酵母生长过程中表现出受损的极化生长。假菌丝和菌丝发育也异常。YlRsr 1对细胞生长也很重要，因为在缺乏Ras GT3 YlRas 2的细胞中缺失YlRSR 1会导致致死性。Y.解脂细胞以两极模式出芽，其中细胞在两极产生新芽。YlRsr 1在芽位选择过程中起着重要作用。YlRsr 1在芽位点选择中的功能绝对需要YlRsr 1在GTP结合状态和GDP结合状态之间的循环，但其在细胞形态发生中的功能不需要，这表明这两个过程受到差异调节。有趣的是，Ras GT3/YlRas 2也参与芽位点选择的控制，因为Ylras 2 Δ细胞在双极芽位点选择中严重受损。GTP/GDP循环和YlRas 2的质膜定位对于YlRas 2在芽位选择中的功能是重要的。然而，它们对于这个过程不是必需的，这表明YlRas 2的作用机制与YlRsr 1的作用机制不同。我们的研究结果表明，YlRsr 1是由GTP酶激活蛋白（GAP）YlBud 2和部分由YlCdc 25，潜在的鸟嘌呤核苷酸交换因子（GEF）的YlRas 2。
ABSTRACT Yarrowia lipolytica is a dimorphic yeast species that can grow in the ovoid yeast form or in the elongated pseudohyphal or hyphal form depending on the growth conditions. Here, we show that the Rap GTPase Rsr1 of Y. lipolytica (YlRsr1) plays an important role in cellular morphogenesis in this microorganism. Cells deleted for YlRSR1 exhibited impaired polarized growth during yeast-form growth. Pseudohyphal and hyphal development were also abnormal. YlRsr1 is also important for cell growth, since the deletion of YlRSR1 in cells lacking the Ras GTPase YlRas2 caused lethality. Y. lipolytica cells bud in a bipolar pattern in which the cells produce the new buds at the two poles. YlRsr1 plays a prominent role in this bud site selection process. YlRsr1's function in bud site selection absolutely requires the cycling of YlRsr1 between the GTP- and GDP-bound states but its function in cellular morphogenesis does not, suggesting that the two processes are differentially regulated. Interestingly, the Ras GTPase YlRas2 is also involved in the control of bud site selection, as Ylras2Δ cells were severely impaired in bipolar bud site selection. The GTP/GDP cycling and the plasma membrane localization of YlRas2 are important for YlRas2's function in bud site selection. However, they are not essential for this process, suggesting that the mechanism by which YlRas2 acts is different from that of YlRsr1. Our results suggest that YlRsr1 is regulated by the GTPase-activating protein (GAP) YlBud2 and partially by YlCdc25, the potential guanine nucleotide exchange factor (GEF) for YlRas2.