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Tracing metabolic pathways of lipid biosynthesis in ectomycorrhizal fungi from position‐specific 13 C‐labelling in glucose
Author(s) -
Scandellari Francesca,
Hobbie Erik A.,
Ouimette Andrew P.,
Stucker Valerie K.
Publication year - 2009
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/j.1462-2920.2009.02013.x
Subject(s) - biology , pentose phosphate pathway , biochemistry , biosynthesis , labelling , glycolysis , metabolic pathway , metabolism , fatty acid , fatty acid synthesis , glyoxylate cycle , lipid metabolism , enzyme
Summary Six position‐specific 13 C‐labelled isotopomers of glucose were supplied to the ectomycorrhizal fungi Suillus pungens and Tricholoma flavovirens. From the resulting distribution of 13 C among fungal PLFAs, the overall order and contribution of each glucose atom to fatty acid 13 C enrichment was: C6 (∼31%) > C5 (∼25%) > C1 (∼18%) > C2 (∼18%) > C3 (∼8%) > C4 (∼1%). These data were used to parameterize a metabolic model of the relative fluxes from glucose degradation to lipid synthesis. Our data revealed that a higher amount of carbon is directed to glycolysis than to the oxidative pentose phosphate pathway (60% and 40% respectively) and that a significant part flows through these pathways more than once (73%) due to the reversibility of some glycolysis reactions. Surprisingly, 95% of carbon cycled through glyoxylate prior to incorporation into lipids, possibly to consume the excess of acetyl‐CoA produced during fatty acid turnover. Our approach provides a rigorous framework for analysing lipid biosynthesis in fungi. In addition, this approach could ultimately improve the interpretation of isotopic patterns at natural abundance in field studies.