Knockout of the Hmt1p Arginine Methyltransferase in Saccharomyces cerevisiae Leads to the Dysregulation of Phosphate-associated Genes and Processes

Abstract

Hmt1p is the predominant arginine methyltransferase in Its substrate proteins are involved in transcription, transcriptional regulation, nucleocytoplasmic transport and RNA splicing. Hmt1p-catalyzed methylation can also modulate protein-protein interactions. Hmt1p is conserved from unicellular eukaryotes through to mammals where its ortholog, PRMT1, is lethal upon knockout. In yeast, however, the effect of knockout on the transcriptome and proteome has not been described. Transcriptome analysis revealed downregulation of phosphate-responsive genes inΔ, including acid phosphatases ,, and , phosphate transporters and and the vacuolar transporter chaperone Analysis of the Δ proteome revealed decreased abundance of phosphate-associated proteins including phosphate transporter Pho84p, vacuolar alkaline phosphatase Pho8p, acid phosphatase Pho3p and subunits of the vacuolar transporter chaperone complex Vtc1p, Vtc3p and Vtc4p. Consistent with this, phosphate homeostasis was dysregulated inΔ cells, showing decreased extracellular phosphatase levels and decreased total P in phosphate-depleted medium. , we showed that transcription factor Pho4p can be methylated at Arg-241, which could explain phosphate dysregulation inΔ if interplay exists with phosphorylation at Ser-242 or Ser-243, or if Arg-241 methylation affects the capacity of Pho4p to homodimerize or interact with Pho2p. However, the Arg-241 methylation site was not validated and the localization of a Pho4p-GFP fusion inΔ was not different from wild type. To our knowledge, this is the first study to reveal an association between Hmt1p and phosphate homeostasis and one which suggests a regulatory link between S-adenosyl methionine and intracellular phosphate.

Type I arginine methyltransferases are intervention points to unveil the oncogenic Epstein-Barr virus to the immune system

“…Arginine methylation occurs on a variety of protein sequence motifs, but the RGG motifs are the most commonly reported ( 38 , 39 ) and, in budding yeast, it is estimated that the majority of arginine methylation occurs in RGG motifs ( 40 ). This is in line with the fact that RGG is the canonical motif substrate established for Hmt1p, a type I PRMT and the main budding yeast PRMT, which is responsible for 66% of arginine monomethylation and 89% of asymmetric dimethylation of intracellular proteins in S. cerevisiae ( 41 ).…”

Global analysis of protein arginine methylation

“…In contrast to HMT1 deletion, deletion of HSL7 showed no significant impact on global ADMA and MMA levels in BY4741 and BY4742 ( Figure 2 B), probably because HSL7 only recognizes a small subset of potential substrate proteins in yeast ( Sayegh and Clarke, 2008 ). Indirect effects associated with the loss of HMT1 are unlikely, as the expression of other PRMTs is not affected by HMT1 knockout ( Chia et al., 2018 )…”

Metabolic consequences of polyphosphate synthesis and imminent phosphate limitation

“…The expression of PHO genes is also under the control of histone methylation: Expression of Pho5 and Pho84 is induced in the set1Δ mutant, which affects methylation of lysine 4 of the nhistone H3 (84, 85). In addition, the methyl transferase Hmt1 promotes expression of several P i -responsive genes (86). Thus, the changes of SAM upon P i starvation might alter the intracellular methylation status and thereby provide a further route of input for P i -dependent gene expression.…”