School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
ACS Infect Dis. 2024 Oct 11;10(10):3528-3543. doi: 10.1021/acsinfecdis.4c00175. Epub 2024 Aug 9.
Ras signaling and glycosylphosphatidylinositol (GPI) biosynthesis are mutually inhibitory in (Sc). The inhibition is mediated via an interaction of yeast Ras2 with the Eri1 subunit of its GPI--acetylglucosaminyl transferase (GPI-GnT), the enzyme catalyzing the very first GPI biosynthetic step. In contrast, Ras signaling and GPI biosynthesis in (Ca) are mutually activated and together control the virulence traits of the human fungal pathogen. What might be the role of Eri1 in this pathogen? The present manuscript addresses this question while simultaneously characterizing the cellular role of CaEri1. It is either nonessential or required at very low levels for cell viability in . Severe depletion of CaEri1 results in reduced GPI biosynthesis and cell wall defects. It also produces hyperfilamentation phenotypes in Spider medium as well as in bicarbonate medium containing 5% CO, suggesting that both the Ras-dependent and Ras-independent cAMP-PKA pathways for hyphal morphogenesis are activated in these cells. Pull-down and acceptor-photobleaching FRET experiments suggest that CaEri1 does not directly interact with CaRas1 but does so through CaGpi2, another GPI-GnT subunit. We showed previously that CaGpi2 is downstream of CaEri1 in cross talk with CaRas1 and for Ras-dependent hyphal morphogenesis. Here we show that CaEri1 is downstream of all GPI-GnT subunits in inhibiting Ras-independent filamentation. also participates in intersubunit transcriptional cross talk within the GPI-GnT, a feature unique to . Virulence studies using larvae show that a heterozygous strain of is better cleared by the host and is attenuated in virulence.
在 （Sc）中，Ras 信号和糖基磷脂酰肌醇（GPI）生物合成是相互抑制的。这种抑制是通过酵母 Ras2 与 GPI-乙酰葡萄糖胺转移酶（GPI-GnT）的 Eri1 亚基相互作用介导的，该酶催化 GPI 生物合成的第一步。相比之下，在 （Ca）中，Ras 信号和 GPI 生物合成是相互激活的，共同控制人类真菌病原体的毒力特征。Eri1 在这种病原体中可能扮演什么角色？本手稿在解决这个问题的同时，还同时描述了 CaEri1 的细胞作用。它在 （Ca）中不是必需的，或者在细胞活力中所需的水平非常低。CaEri1 的严重耗竭导致 GPI 生物合成减少和细胞壁缺陷。它还在 Spider 培养基和含有 5%CO 的碳酸氢盐培养基中产生超丝状表型，这表明 Ras 依赖性和 Ras 非依赖性 cAMP-PKA 途径都在这些细胞中被激活。下拉和受体光漂白 FRET 实验表明，CaEri1 不与 CaRas1 直接相互作用，但通过另一个 GPI-GnT 亚基 CaGpi2 相互作用。我们之前表明，CaGpi2 在与 CaRas1 的交叉对话中是 CaEri1 的下游，并且是 Ras 依赖性菌丝形态发生的下游。在这里，我们表明 CaEri1 是所有 GPI-GnT 亚基下游的，抑制 Ras 非依赖性丝状形成。 （Sc）也参与 GPI-GnT 中的亚基间转录交叉对话，这是 的一个独特特征。使用 幼虫进行的毒力研究表明， 杂合菌株更容易被宿主清除，并且在毒力方面减弱。
