Phosphorylated Gβ is a directional cue during yeast gradient tracking
Phosphorylated Gβ is a directional cue during yeast gradient tracking
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DOI：
10.1126/scisignal.abf4710
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发表时间：
2021-05-11
影响因子：
7.3
通讯作者：
Stone, David E.
中科院分区：
文献类型：
--
作者：
Abdul-Ganiyu, Rashida;Venegas, Leon A.;Stone, David E.
出芽酵母细胞解释来自相反交配类型细胞的浅信息素梯度，使它们的生长向信息素源极化，并在趋化生长位点融合。我们之前提出了一个确定性的梯度传感模型，该模型解释了酵母细胞如何从质膜上固有定位的默认极性位点（DS）切换到梯度对齐的趋化位点（CS）。由于交配特异性 G β 亚基的磷酸化被认为对此过程很重要，因此我们开发了一种生物传感器，可以与磷酸化但不与未磷酸化的 G β 结合，并监测其时空动态，以测试我们的梯度传感模型的关键预测。在交配细胞中，生物传感器与 DS 处的 G beta 和受体报告基因共定位，然后与它们一起追踪到 CS。生物传感器集中在跟踪Gβ和受体峰值的前沿，并且是第一个到达并停止跟踪CS的。我们的数据表明，磷酸化Gβ的集中定位与G蛋白和受体的跟踪方向和最终位置相关，这与Gβ的梯度调节磷酸化和去磷酸化有助于梯度传感的观点一致。表达不可磷酸化的 G beta 突变体的细胞在梯度跟踪、交配伙伴定向和交配效率方面表现出缺陷。
Budding yeast cells interpret shallow pheromone gradients from cells of the opposite mating type, polarize their growth toward the pheromone source, and fuse at the chemotropic growth site. We previously proposed a deterministic, gradient-sensing model that explains how yeast cells switch from the intrinsically positioned default polarity site (DS) to the gradient-aligned chemotropic site (CS) at the plasma membrane. Because phosphorylation of the mating-specific G beta subunit is thought to be important for this process, we developed a biosensor that bound to phosphorylated but not unphosphorylated G beta and monitored its spatiotemporal dynamics to test key predictions of our gradient-sensing model. In mating cells, the biosensor colocalized with both G beta and receptor reporters at the DS and then tracked with them to the CS. The biosensor concentrated on the leading side of the tracking G beta and receptor peaks and was the first to arrive and stop tracking at the CS. Our data showed that the concentrated localization of phosphorylated G beta correlated with the tracking direction and final position of the G protein and receptor, consistent with the idea that gradient-regulated phosphorylation and dephosphorylation of G beta contributes to gradient sensing. Cells expressing a nonphosphorylatable mutant form of G beta exhibited defects in gradient tracking, orientation toward mating partners, and mating efficiency.