Effect of vitamin B6 availability on serine hydroxymethyltransferase in MCF-7 cells.

Article Details

Citation

Copy to clipboard

Perry C, Yu S, Chen J, Matharu KS, Stover PJ

Effect of vitamin B6 availability on serine hydroxymethyltransferase in MCF-7 cells.

Arch Biochem Biophys. 2007 Jun 1;462(1):21-7. Epub 2007 Apr 20.

PubMed ID

17482557 [ View in PubMed

]

Abstract

Folate-activated one-carbon units are derived from serine through the activity of the pyridoxal-phosphate (PLP)-dependent isozymes of serine hydroxymethyltransferase (SHMT). The effect of vitamin B(6) availability on the activity and expression of the human mitochondrial and cytoplasmic SHMT isozymes was investigated in human MCF-7 cells. Cells were cultured for 6 months in vitamin B(6) replete (4.9 microM pyridoxine) minimal essential medium (alphaMEM) or vitamin B(6)-deficient medium containing 49, 4.9 or 0.49 nM pyridoxine. Total cellular PLP levels and SHMT activity were reduced 72% and 7%, respectively, when medium pyridoxine was decreased from 4.9 microM to 49 nM. Cells cultured in medium containing 4.9 nM pyridoxine exhibited 75%, 27% and 60% reduced levels of PLP, SHMT activity and S-adenosylmethionine, respectively, compared to cells cultured in alphaMEM. Cytoplasmic SHMT activity and protein levels, but not mRNA levels, were decreased in cells cultured in vitamin B(6) deficient medium, whereas mitochondrial SHMT activity and protein levels were less sensitive to vitamin B(6) availability. PLP bound to cytoplasmic SHMT with a K(d)=850 nM, a value two orders of magnitude lower than previously reported for the bovine cytoplasmic SHMT isozyme. Collectively, these data indicate that vitamin B(6) restriction decreases the activity and stability of SHMT, and that the cytoplasmic isozyme is more sensitive to vitamin B(6) deficiency than the mitochondrial isozyme in MCF-7 cells.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Pyridoxal phosphate	Serine hydroxymethyltransferase, mitochondrial	Protein	Humans	Unknown	Cofactor	Details