Laboratory of Molecular Microbiology, School of Biological Sciences and Institute of Microbiology, Seoul National University, Korea.
Korea Polar Research Institute, Incheon, Korea.
FEBS J. 2020 Mar;287(5):878-896. doi: 10.1111/febs.15052. Epub 2019 Sep 18.
Glucose limitation is a major stress condition that cells must respond to by altering their metabolism to ensure survival. Rsv1 is a zinc finger protein previously shown to be required for survival during stationary phase. In this study, we present a novel mechanism regulated by Rsv1 in the fission yeast Schizosaccharomyces pombe that is involved in altering glucose metabolic flux. We found that rsv1 gene expression is induced by Rst2 and Atf1, two transcription factors regulated by the cAMP-dependent protein kinase (PKA) pathway and the mitogen-activated protein kinase (MAPK) cascade, respectively. The downstream target genes of Rsv1 were identified by genome-wide ChIP sequencing of Rsv1-bound DNA sites and RNA sequencing analysis of Rsv1-dependent transcripts that were differentially expressed under glucose starvation. Rsv1 directly regulated the expression of at least 21 genes that mostly encode transporters and proteins related to sugar metabolism. Among these, gcd1, which encodes glucose dehydrogenase in the gluconate shunt for the pentose phosphate pathway, was most remarkably repressed by Rsv1. The defect in survival of Δrsv1 mutant under glucose starvation condition was mitigated by additional deletion of a gcd1, idn1, or a gene for a putative lactonase (SPCC16c4.10), suggesting the critical importance of downregulating the gluconate shunt and pentose phosphate pathway for long-term survival. These results show an intricate response to glucose starvation: increasing the synthesis of a transcription factor via two signal transduction pathways, which sheds light on the importance of remodeling a metabolic circuit to secure glucose for cell survival.
葡萄糖限制是细胞必须应对的主要应激条件，通过改变代谢来确保生存。Rsv1 是一种锌指蛋白，先前被证明是在停滞期存活所必需的。在这项研究中，我们提出了一种裂殖酵母 Schizosaccharomyces pombe 中由 Rsv1 调节的新机制，该机制涉及改变葡萄糖代谢通量。我们发现，rsv1 基因的表达受 Rst2 和 Atf1 的诱导，这两个转录因子分别受 cAMP 依赖性蛋白激酶 (PKA) 途径和丝裂原激活蛋白激酶 (MAPK) 级联的调节。通过 Rsv1 结合 DNA 位点的全基因组 ChIP 测序和 Rsv1 依赖的转录本的 RNA 测序分析，确定了 Rsv1 的下游靶基因，这些转录本在葡萄糖饥饿下差异表达。Rsv1 直接调节至少 21 个基因的表达，这些基因主要编码糖代谢相关的转运蛋白和蛋白质。其中，gcd1 编码戊糖磷酸途径中葡糖酸盐支路的葡萄糖脱氢酶，受 Rsv1 的显著抑制。在葡萄糖饥饿条件下，Δrsv1 突变体的生存缺陷通过进一步缺失 gcd1、idn1 或一个假定的内酯酶 (SPCC16c4.10) 的基因得到缓解，这表明下调葡糖酸盐支路和戊糖磷酸途径对于长期生存至关重要。这些结果显示了对葡萄糖饥饿的复杂反应：通过两条信号转导途径增加转录因子的合成，这表明重塑代谢电路以确保细胞生存所需的葡萄糖的重要性。
