A novel regulatory mechanism for serine biosynthesis

June 14, 2017

Serine biosynthesis enzyme regulated through multiple amino acids

RIKEN CSRS researchers have discovered a new serine biosynthetic control mechanism in Arabidopsis associated with the enzyme 3-phosphoglycerate dehydrogenase (PGDH).

Serine biosynthesis occurs via the phosphorylated pathway. In microorganisms, an increase in cellular serine concentrations inhibits the activity of PGDH, which is the first enzyme in the phosphorylated pathway, while a lowered serine concentration increases PGDH activity. As such, PGDH activity was thought to be regulated only by serine concentrations, and the details of PGDH activity regulation in plants remained unclarified.

The CSRS research team expressed three Arabidopsis PDGH isoenzyme genes (PGDH1, PGDH2, PGDH3), in E. coli, prepared their recombinant proteins and observed their enzymatic activity in vitro. By adding each of 43 amino acids to an enzymatic reaction mixture and observing the changes in activity, the researchers discovered that PDGH1 and PGDH3 activity was inhibited by L-serine but promoted by L-alanine, L-valine, L-methionine, L-homoserine and L-homocysteine. This finding suggests that control of serine biosynthesis in Arabidopsis is more complex than previously thought and that the various cell processes involving serine are likely controlled by this newly discovered regulatory mechanism.

This finding is expected to provide new insights into understanding biological phenomena and the evolutionary implications of serine biosynthetic control.

Original article
Scientific Reports doi:10.1038/s41598-017-03807-5
E. Okamura, M. Y. Hirai,
"Novel regulatory mechanism of serine biosynthesis associated with 3-phosphoglycerate dehydrogenase in Arabidopsis thaliana".
Eiji Okamura; Postdoctoral Researcher
Masami Hirai; Team Leader
Metabolic Systems Research Team