Glucose Inhibits Yeast AMPK (Snf1) by Three Independent Mechanisms

Abstract

Snf1, the fungal homologue of mammalian AMP-dependent kinase (AMPK), is a key protein kinase coordinating the response of cells to a shortage of glucose. In fungi, the response is to activate respiratory gene expression and metabolism. The major regulation of Snf1 activity has been extensively investigated: In the absence of glucose, it becomes activated by phosphorylation of its threonine at position 210. This modification can be erased by phosphatases when glucose is restored. In the past decade, two additional independent mechanisms of Snf1 regulation have been elucidated. In response to glucose (or, surprisingly, also to DNA damage), Snf1 is SUMOylated by Mms21 at lysine 549. This inactivates Snf1 and leads to Snf1 degradation. More recently, glucose-induced proton export has been found to result in Snf1 inhibition via a polyhistidine tract (13 consecutive histidine residues) at the N-terminus of the Snf1 protein. Interestingly, the polyhistidine tract plays also a central role in the response to iron scarcity. This review will present some of the glucose-sensing mechanisms of S. cerevisiae, how they interact, and how their interplay results in Snf1 inhibition by three different, and independent, mechanisms.

The Plasma Membrane H+ ATPase CsPMA2 Regulates Lipid Droplet Formation, Appressorial Development and Virulence in Colletotrichum siamense

“…It was reported that plasma membrane P-type ATPase is a type of transport protein localized in the plasma membrane and is responsible for pumping hydrogen proteins from the cytoplasm to the extracellular space to maintain intracellular pH and ion homeostasis [7][8][9]. There are two plasma membrane H + -ATPases, PMA1 and PMA2, in fungi [10][11][12].…”

“…According to the properties of its transport substances, the plasma membrane transport P-type ATPase can be divided into multiple subtypes, including sodium potassium pump (Na + /K + -ATPase), calcium pump (Ca 2+ -ATPase), proton pump (H + -ATPase), and heavy metal pump [5,6]. Among these subtypes, plasma membrane H + -ATPase is a type of hydrogen proton pump driven by ATP, which is responsible for pumping hydrogen protons from the cytoplasm to the extracellular space to maintain intracellular pH and ion homeostasis, form transmembrane electrochemical potential, and promote nutrient transportation and the expulsion of secondary metabolites [7][8][9]. Most fungi have two plasma membrane H + -ATPases, PMA1 and PMA2 [10][11][12][13].…”