TheSaccharomyces cerevisiae PHM8Gene Encodes a Soluble Magnesium-dependent Lysophosphatidic Acid Phosphatase

Venky Sreedhar Reddy, Arjun Kumar Singh, Ram Rajasekharan
2008 Journal of Biological Chemistry  
Phosphate is the essential macronutrient required for the growth of all organisms. In Saccharomyces cerevisiae, phosphatases are up-regulated, and the level of lysophosphatidic acid (LPA) is drastically decreased under phosphate-starved conditions. The reduction in the LPA level is attributed to PHM8, a gene of unknown function. phm8⌬ yeast showed a decreased LPA-hydrolyzing activity under phosphate-limiting conditions. Overexpression of PHM8 in yeast resulted in an increase in the LPA
more » ... in the LPA phosphatase activity in vivo. In vitro assays of the purified recombinant Phm8p revealed magnesium-dependent LPA phosphatase activity, with maximal activity at pH 6.5. The purified Phm8p did not hydrolyze any lipid phosphates other than LPA. In silico analysis suggest that Phm8p is a soluble protein with no transmembrane domain. Site-directed mutational studies revealed that aspartate residues in a DXDXT motif are important for the catalysis. These findings indicated that LPA plays a direct role in phosphate starvation. This is the first report of the identification and characterization of magnesiumdependent soluble LPA phosphatase.
doi:10.1074/jbc.m706752200 pmid:18234677 fatcat:z2r5pkphczdidnskahtdbjmviq