Yun, C.-H. | Search bioRxiv

bioRxiv2023

Structure of a fungal 1,3-β-glucan synthase

1,3-{beta}-Glucan is the major component of the fungal cell wall and is synthesized by 1,3-{beta}-glucan synthase located in the plasma membrane, which is a molecular target of anti-fungal drugs echinocandins and the triterpenoid ibrexafungerp. In this study, we report the 3.0-[A] resolution cryo-EM structure of Saccharomyces cerevisiae 1,3-{beta}-glucan synthase, Fks1. The structure reveals a central catalytic region adopting a cellulose synthase fold with a cytosolic conserved GT-A type glycosyltransferase domain and a closed transmembrane glucan-transporting channel. We found that two extracellular disulfide bonds are crucial for Fks1 enzymatic activity. Structural comparison between Fks1 and cellulose synthases and structure-guided mutagenesis studies provided novel insights into the molecular mechanisms of the fungal 1,3-{beta}-glucan synthase.

biophysics↗

bioRxiv2021

Protein-Metabolite Interactomics Reveals Novel Regulation of Carbohydrate Metabolism

Metabolism is highly interconnected and also has profound effects on other cellular processes. However, the interactions between metabolites and proteins that mediate this connectivity are frequently low affinity and difficult to discover, hampering our understanding of this important area of cellular biochemistry. Therefore, we developed the MIDAS platform, which can identify protein-metabolite interactions with great sensitivity. We analyzed 33 enzymes from central carbon metabolism and identified 830 protein-metabolite interactions that were mostly novel, but also included known regulators, substrates, products and their analogs. We validated previously unknown interactions, including two atomic-resolution structures of novel protein-metabolite complexes. We also found that both ATP and long-chain fatty acyl-CoAs inhibit lactate dehydrogenase A (LDHA), but not LDHB, at physiological concentrations in vitro. Treating cells with long-chain fatty acids caused a loss of pyruvate/lactate interconversion, but only in cells reliant on LDHA. We propose that these regulatory mechanisms are part of the metabolic connectivity that enables survival in an ever-changing nutrient environment, and that MIDAS enables a broader and deeper understanding of that network.

biochemistry↗