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bioRxiv · 10.1101/2023.12.14.571224

Structural basis of S-adenosylmethionine-dependent Allosteric Transition from Active to Inactive States in Methylenetetrahydrofolate Reductase

Yamada, K.·Mendoza, J.·Koutmos, M.
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Abstract

Methylenetetrahydrofolate reductase (MTHFR) is a pivotal flavoprotein connecting the folate and methionine methyl cycles, catalyzing the conversion of methylenetetrahydrofolate to methyltetrahydrofolate. Human MTHFR (hMTHFR) undergoes elaborate allosteric regulation involving protein phosphorylation and AdoMet-dependent inhibition, though other factors such as subunit orientation and FAD status remain understudied due to the lack of a functional structural model. Here, we report crystal structures of Chaetomium thermophilum MTHFR (cMTHFR) in both active (R) and inhibited (T) states. We reveal FAD occlusion by Tyr361 in the T-state, which prevents substrate interaction. Remarkably, the inhibited form of cMTHFR accommodates two AdoMet molecules per subunit. In addition, we conducted a detailed investigation of the phosphorylation sites in hMTHFR, three of which are novel. Based on the structural framework provided by our cMTHFR model, we propose a possible mechanism to explain the allosteric structural transition of MTHFR, including the impact of phosphorylation on AdoMet-dependent inhibition.

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Yamada, K., Mendoza, J., Koutmos, M.. 2023-12-14. Structural basis of S-adenosylmethionine-dependent Allosteric Transition from Active to Inactive States in Methylenetetrahydrofolate Reductase. https://doi.org/10.1101/2023.12.14.571224

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