Cancer‐associated mutations in human pyruvate kinase M2 impair enzyme activity

Abstract

Mammalian pyruvate kinase catalyzes the final step of glycolysis, and its M2 isoform (PKM2) is widely expressed in proliferative tissues. Mutations in PKM2 are found in some human cancers; however, the effects of these mutations on enzyme activity and regulation are unknown. Here, we characterized five cancer‐associated PKM2 mutations, occurring at various locations on the enzyme, with respect to substrate kinetics and activation by the allosteric activator fructose‐1,6‐bisphosphate (FBP). The mutants exhibit reduced maximal velocity, reduced substrate affinity, and/or altered activation by FBP. The kinetic parameters of five additional PKM2 mutants that have been used to study enzyme function or regulation also demonstrate the deleterious effects of mutations on PKM2 function. Our findings indicate that PKM2 is sensitive to many amino acid changes and support the hypothesis that decreased PKM2 activity is selected for in rapidly proliferating cells.

Structural basis for allosteric regulation of pyruvate kinase M2 by phosphorylation and acetylation

“…All variants have a reduced FBP binding affinity (Kd of ~0.6-7 µM) relative to wtPKM2 (Kd= 0.98±0.1 nM) ( Fig. 4A-C), consistwnt with a recent report showing that the K433E variant has reduced FBP binding affinity compared to wtPKM2 (23). These results imply that in addition to mutation of a residue in the FBP binding pocket (E433) and K433 acetylation (Q433), interestingly, phosphorylation at S37, which is in the Nterminus, also leads to a decrease in the FBP binding affinity of PKM2.…”

“…The crystal structure of wtPKM2-FBP (PDB: 1T5A) (9) illustrates that K433 is present in the FBP binding pocket of PKM2 and interacts with FBP. Therefore, acetylation (17) or mutation of PKM2 (23,24) reduces its FBP binding affinity. Using wholecell lysate of PKM2 acetylated at K433 and a recombinant acetyl-lysine mimetic variant of PKM2 (hereafter, PKM2 K433Q), gel filtration studies determined that the enzyme appeared in the dimeric and a mixture of monomeric/dimeric states respectively, consequently resulting in its translocation to the nucleus (6,8).…”

From Glucose to Lactate and Transiting Intermediates Through Mitochondria, Bypassing Pyruvate Kinase: Considerations for Cells Exhibiting Dimeric PKM2 or Otherwise Inhibited Kinase Activity

“…Therefore, a switch from PKM1 to PKM2 isoform expression during malignant transformation may not be taking place, as previously postulated (Christofk et al, 2008). Mindful of the controversy surrounding the proposed functions of PKM2 (Hosios et al, 2015;Harris and Fenton, 2019), the group of Vander Heiden characterized the effects of cancer−associated PKM2 mutations on enzyme kinetics and allosteric regulation and reported that a decrease in PKM2 activity supports the rapid proliferation of cells (Liu V. M. et al, 2020). This is in line with earlier reports showing that a decrease in PKM2 activity due to posttranslational modifications (Lv et al, 2011) or inhibition by oxidative stress (Anastasiou et al, 2011) promotes tumor growth (Prakasam et al, 2018).…”

WITHDRAWN: Prognostic Significance of Pyruvate Kinase M2 Expression in Esophageal Squamous Cell Carcinoma and Its Meta-Analysis

“…The activity of PKM2 is regulated by a variety of post-translational modi cations, such as phosphorylation, acetylation, sumoylation, hydroxylation, and oxidation, which prefer the formation of dimer PKM2 in tumor cells [18,19]. PKM2 mutations can also change activity [20]. A study proved that PKM2 activity is also down-regulated by oxidation of C358 by ROS or hypoxia, leading to switching of the ux of glucose into the pentose phosphate pathway and glycolytic biosynthesis to generate NADPH for ROS detoxi cation and tumor progression [21].…”