经典极性机制在芽殖酵母孢子极性从头建立中的作用。

Roles for the canonical polarity machinery in the de novo establishment of polarity in budding yeast spores.

作者信息

Cooperman Benjamin, McMurray Michael

机构信息

Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045.

出版信息

Mol Biol Cell. 2025 Mar 1;36(3):ar28. doi: 10.1091/mbc.E24-07-0303. Epub 2025 Jan 22.

Abstract

The yeast buds at sites predetermined by cortical landmarks deposited during prior budding. During mating between haploid cells in the lab, external pheromone cues override the cortical landmarks to drive polarization and cell fusion. By contrast, in haploid gametes (called spores) produced by meiosis, a predetermined polarity site drives initial polarized morphogenesis independent of mating partner location. Spore membranes are made so existing cortical landmarks were unknown, as were the mechanisms by which the spore polarity site is made and how it works. We find that the landmark canonically required for distal budding, Bud8, stably marks the spore polarity site along with Bud5, a GEF for the GTPase Rsr1 that canonically links cortical landmarks to the conserved Cdc42 polarity machinery. Cdc42 and other GTPase regulators arrive at the site during its biogenesis, after spore membrane closure but apparently at the site where membrane synthesis began, and then these factors leave, pointing to the presence of discrete phases of maturation. Filamentous actin may be required for initial establishment of the site, but thereafter Bud8 accumulates independent of actin filaments. These results suggest a distinct polarization mechanism that may provide insights into gamete polarization in other organisms.

摘要

酵母在先前出芽过程中沉积的皮质标记所预先确定的位点出芽。在实验室单倍体细胞之间的交配过程中,外部信息素线索会覆盖皮质标记,以驱动细胞极化和融合。相比之下,在减数分裂产生的单倍体配子(称为孢子)中,一个预先确定的极性位点驱动初始极化形态发生,而与交配伙伴的位置无关。由于孢子膜形成时,现有的皮质标记尚不清楚,孢子极性位点的形成机制及其工作方式也不清楚。我们发现,通常用于远端出芽的标记Bud8与Bud5一起稳定地标记孢子极性位点,Bud5是GTP酶Rsr1的鸟嘌呤核苷酸交换因子,它通常将皮质标记与保守的Cdc42极性机制联系起来。Cdc42和其他GTP酶调节因子在孢子膜闭合后,但显然在膜合成开始的位点处,在孢子极性位点形成过程中到达该位点,然后这些因子离开,这表明存在不同的成熟阶段。丝状肌动蛋白可能是该位点初始建立所必需的,但此后Bud8的积累独立于肌动蛋白丝。这些结果提示了一种独特的极化机制,这可能为深入了解其他生物体中的配子极化提供线索。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/abd7/11974964/ab6cd58b4cac/mbc-36-ar28-g001.jpg

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