Large enrichments in fatty acid 2H/1H ratios distinguish respiration from aerobic fermentation in yeast Saccharomyces cerevisiae

• 成果类型: Article
• 署名作者: Maloney, Ashley E.; Kopf, Sebastian H.; Zhang, Zhaoyue; Mcfarlin, Jamie; Nelson, Daniel B.; Masterson, Andrew L.; Zhang, Xinning
• 署名单位: Princeton University; University of Colorado System; University of Colorado Boulder; Princeton University; Princeton University; University of Wyoming; University of Basel; Northwestern University; Princeton University
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13702
• DOI: 10.1073/pnas.2310771121
• 发表日期: 2024-05-14
• 关键词: pentose-phosphate pathway; phase escherichia-coli; isotope fractionation; intracellular water; carbon; GROWTH; mechanism; enzyme; lipids; metabolism

摘要

Shifts in the hydrogen stable isotopic composition (H-2/H-1 ratio) of lipids relative to water (lipid/water H-2-fractionation) at natural abundances reflect different sources of the central cellular reductant, NADPH, in bacteria. Here, we demonstrate that lipid/water H-2-fractionation ((2)epsilon(fattyacid/water)) can also constrain the relative importance of key NADPH pathways in eukaryotes. We used the metabolically flexible yeast Saccharomyces cerevisiae, a microbial model for respiratory and fermentative metabolism in industry and medicine, to investigate (2)epsilon(fattyacid/water). In chemostats, fatty acids from glycerol-respiring cells were >550 parts per thousand H-2-enriched compared to those from cells aerobically fermenting sugars via overflow metabolism, a hallmark feature in cancer. Faster growth decreased H-2/H-1 ratios, particularly in glycerol-respiring cells by 200 parts per thousand. Variations in the activities and kinetic isotope effects among NADP(+)-reducing enzymes indicate cytosolic NADPH supply as the primary control on (2)epsilon(fattyacid/water). Contributions of cytosolic isocitrate dehydrogenase (cIDH) to NAPDH production drive large H-2-enrichments with substrate metabolism (cIDH is absent during fermentation but contributes up to 20 percent NAPDH during respiration) and slower growth on glycerol (11 percent more NADPH from cIDH). Shifts in NADPH demand associated with cellular lipid abundance explain smaller (2)epsilon(fattyacid/water) variations (<30 parts per thousand) with growth rate during fermentation. Consistent with these results, tests of murine liver cells had H-2-enriched lipids from slower-growing, healthy respiring cells relative to fast-growing, fermenting hepatocellular carcinoma. Our findings point to the broad potential of lipid H-2/H-1 ratios as a passive natural tracker of eukaryotic metabolism with applications to distinguish health and disease, complementing studies that rely on complex isotope-tracer addition methods.