Abstract
The pyruvate dehydrogenase complex (PDC) is a multienzyme complex that plays a key role in energy metabolism by converting pyruvate to acetyl-CoA. An increase of nuclear PDC has been shown to be correlated with an increase of histone acetylation that requires acetyl-CoA. PDC has been reported to form a ~ 10 MDa macromolecular machine that is proficient in performing sequential catalytic reactions via its three components. In this study, we show that the PDC displays size versatility in an ionic strength-dependent manner using size exclusion chromatography of yeast cell extracts. Biochemical analysis in combination with mass spectrometry indicates that yeast PDC (yPDC) is a salt-labile complex that dissociates into sub-megadalton individual components even under physiological ionic strength. Interestingly, we find that each oligomeric component of yPDC displays a larger size than previously believed. In addition, we show that the mammalian PDC also displays this uncommon characteristic of salt-lability, although it has a somewhat different profile compared to yeast. We show that the activity of yPDC is reduced in higher ionic strength. Our results indicate that the structure of PDC may not always maintain its ~ 10 MDa organization, but is rather variable. We propose that the flexible nature of PDC may allow modulation of its activity.
Highlights
The multienzyme pyruvate dehydrogenase complex (PDC) catalyzes the reaction that generates acetyl-CoA from pyruvate, the end-product of glucose breakdown
To facilitate the detection of the PDC components, yeast BY4741 strains were generated in which combinations of the E1p β subunit (E1pβ), E2p and E3 were epitopetagged at their endogenous locus with 3xHA, V5 and 5xFLAG, respectively
The PDC subunit tagged strains, did not display such rapamycin sensitivity compared to wildtype (S1 Fig in S1 File), the epitope tags did not cause a cellular dysfunction of PDC
Summary
The multienzyme pyruvate dehydrogenase complex (PDC) catalyzes the reaction that generates acetyl-CoA from pyruvate, the end-product of glucose breakdown. The PDC plays a central role as a gatekeeper of energy and glucose homeostasis. Consistent with its important role in metabolism, low PDC activity arising from mutations of its components causes a PDC deficiency (PDCD) [1]. PDCD patients have a low survival rate and suffer from ataxia and neurodevelopmental delay. This arises from a failure to produce enough energy as the tricarboxylic acid (TCA) cycle, which links glycolysis to electron transport chain for ATP.
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