A New Nuclear Function of the Entamoeba histolytica Glycolytic Enzyme Enolase: The Metabolic Regulation of Cytosine-5 Methyltransferase 2 (Dnmt2) Activity

Abstract

Cytosine-5 methyltransferases of the Dnmt2 family function as DNA and tRNA methyltransferases. Insight into the role and biological significance of Dnmt2 is greatly hampered by a lack of knowledge about its protein interactions. In this report, we address the subject of protein interaction by identifying enolase through a yeast two-hybrid screen as a Dnmt2-binding protein. Enolase, which is known to catalyze the conversion of 2-phosphoglycerate (2-PG) to phosphoenolpyruvate (PEP), was shown to have both a cytoplasmatic and a nuclear localization in the parasite Entamoeba histolytica. We discovered that enolase acts as a Dnmt2 inhibitor. This unexpected inhibitory activity was antagonized by 2-PG, which suggests that glucose metabolism controls the non-glycolytic function of enolase. Interestingly, glucose starvation drives enolase to accumulate within the nucleus, which in turn leads to the formation of additional enolase-E.histolytica DNMT2 homolog (Ehmeth) complex, and to a significant reduction of the tRNAAsp methylation in the parasite. The crucial role of enolase as a Dnmt2 inhibitor was also demonstrated in E.histolytica expressing a nuclear localization signal (NLS)-fused-enolase. These results establish enolase as the first Dnmt2 interacting protein, and highlight an unexpected role of a glycolytic enzyme in the modulation of Dnmt2 activity.

Age-dependent Effects of 17β-estradiol on the Dynamics of Estrogen Receptor β (ERβ) Protein–Protein Interactions in the Ventral Hippocampus

“…In fact, actin has an essential transcriptional role in the nucleus (60 -62). Actin serves as a scaffold to assist in gene regulation and also is a key component in nuclear export, as suggested by the leucine-rich nuclear export signal within actin that has aided in nuclear export of viral RNA (63,64). Thus, we hypothesize that the changes in interactions between ER␤ and actin-associated proteins such as GELS and ENO1, which has been shown to modulate DNA methyltransferase (65), could be a result of changes in nuclear actin structure (59).…”

The Entamoeba histolytica Dnmt2 Homolog (Ehmeth) Confers Resistance to Nitrosative Stress

“…histolytica belongs to the so-called family of "Dnmt2-only" organisms, in that it does not contain any of the canonical DNA methyltransferases (Dnmt1 and Dnmt3). E. histolytica Dnmt2 (Ehmeth) is a weak, but genuine, DNA methyltransferase (6)(7)(8), and its ability to catalyze tRNA Asp methylation has been recently demonstrated (9). This dual specificity of Ehmeth for DNA and tRNA has also been proposed for the Dnmt2 homolog in Drosophila melanogaster (10).…”

“…We have recently reported that glucose starvation, with the help of the glycolytic enzyme enolase, regulates the parasite's methylation status (9). Enolase interacts with the catalytic site of Ehmeth and inhibits its methyltransferase activity.…”

The identification and characterization of non-coding and coding RNAs and their modified nucleosides by mass spectrometry

“…Moreover, homologs have been found in many organisms outside of vertebrates including Schizosaccharomyces pombe, Dictyostelium discoideum, Entamoeba hystolitica, and the bacterium Geobacter sulfurreducens, to name a few. [60][61][62][63] Limitations of the RNA modification mapping approach One limitation of the traditional RNA modification mapping approach by MS is the reliance on mass differences to identify the sequence location for a modified nucleoside. Modifications that share the same mass value, e.g., methylations such as 7-methylguanosine (m 7 G), 1-methylguanosine (m 1 G), N 2 -methylguanosine (m 2 G) and 2'-O-methylguanosine, cannot be differentiated within the MS/MS data.…”