Metformin Is a Pyridoxal-5'-phosphate (PLP)-Competitive Inhibitor of SHMT2
dc.contributor.author
dc.date.accessioned
2022-03-21T14:44:10Z
dc.date.available
2022-03-21T14:44:10Z
dc.date.issued
2021-08-09
dc.identifier.uri
dc.description.abstract
The anticancer actions of the biguanide metformin involve the functioning of the serine/glycine one-carbon metabolic network. We report that metformin directly and specifically targets the enzymatic activity of mitochondrial serine hydroxymethyltransferase (SHMT2). In vitro competitive binding assays with human recombinant SHMT1 and SHMT2 isoforms revealed that metformin preferentially inhibits SHMT2 activity by a non-catalytic mechanism. Computational docking coupled with molecular dynamics simulation predicted that metformin could occupy the cofactor pyridoxal-5'-phosphate (PLP) cavity and destabilize the formation of catalytically active SHMT2 oligomers. Differential scanning fluorimetry-based biophysical screening confirmed that metformin diminishes the capacity of PLP to promote the conversion of SHMT2 from an inactive, open state to a highly ordered, catalytically competent closed state. CRISPR/Cas9-based disruption of SHMT2, but not of SHMT1, prevented metformin from inhibiting total SHMT activity in cancer cell lines. Isotope tracing studies in SHMT1 knock-out cells confirmed that metformin decreased the SHMT2-channeled serine-to-formate flux and restricted the formate utilization in thymidylate synthesis upon overexpression of the metformin-unresponsive yeast equivalent of mitochondrial complex I (mCI). While maintaining its capacity to inhibit mitochondrial oxidative phosphorylation, metformin lost its cytotoxic and antiproliferative activity in SHMT2-null cancer cells unable to produce energy-rich NADH or FADH2 molecules from tricarboxylic acid cycle (TCA) metabolites. As currently available SHMT2 inhibitors have not yet reached the clinic, our current data establishing the structural and mechanistic bases of metformin as a small-molecule, PLP-competitive inhibitor of the SHMT2 activating oligomerization should benefit future discovery of biguanide skeleton-based novel SHMT2 inhibitors in cancer prevention and treatment
dc.format.mimetype
application/pdf
dc.language.iso
eng
dc.publisher
MDPI (Multidisciplinary Digital Publishing Institute)
dc.relation.isformatof
Reproducció digital del document publicat a: https://doi.org/10.3390/cancers13164009
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Cancers, 2021, vol. 13, núm. 16, p. 4009
dc.relation.ispartofseries
Articles publicats (IdIBGi)
dc.rights
Attribution 4.0 International (CC BY 4.0)
dc.rights.uri
dc.source
Tramonti, Angela Cuyàs, Elisabet Encinar, José Antonio Pietzke, Matthias Paone, Alessio Verdura, Sara Arbusà, Aina Martin Castillo, Begoña Giardina, Giorgio Joven, Jorge Vázquez, Alexei Contestabile, Roberto Cutruzzolà, Francesca Menéndez Menéndez, Javier Abel 2021 Metformin Is a Pyridoxal-5'-phosphate (PLP)-Competitive Inhibitor of SHMT2 Cancers 13 16 4009
dc.subject
dc.title
Metformin Is a Pyridoxal-5'-phosphate (PLP)-Competitive Inhibitor of SHMT2
dc.type
info:eu-repo/semantics/article
dc.rights.accessRights
info:eu-repo/semantics/openAccess
dc.type.version
info:eu-repo/semantics/publishedVersion
dc.identifier.doi
dc.identifier.idgrec
034561
dc.type.peerreviewed
peer-reviewed
dc.identifier.eissn
2072-6694