The LPP1 and DPP1 Gene Products Account for Most of the Isoprenoid Phosphate Phosphatase Activities inSaccharomyces cerevisiae

Abstract

Two genes in2؉ -independent hydrolysis of several isoprenoid phosphates by particulate fractions isolated from these cells. The particulate and cytosolic fractions from the double disruption (lpp1⌬ dpp1⌬) showed essentially complete loss of Mg 2؉ -independent hydrolytic activity toward dolichyl phosphate (dolichyl-P), dolichyl pyrophosphate (dolichyl-P-P), farnesyl pyrophosphate (farnesyl-P-P), and geranylgeranyl pyrophosphate (geranylgeranyl-P-P). However, a modest Mg 2؉ -stimulated activity toward PA and dolichyl-P was retained in cytosol from lpp1⌬ dpp1⌬ cells. The action of Dpp1p on isoprenyl pyrophosphates was confirmed by characterization of the hydrolysis of geranylgeranyl-P-P by the purified protein. These results indicate that LPP1 and DPP1 account for most of the hydrolytic activities toward dolichyl-P-P, dolichyl-P, farnesyl-P-P, and geranylgeranyl-P-P but also suggest that yeast contain other enzymes capable of dephosphorylating these essential isoprenoid intermediates.Phosphorylated lipids serve diverse roles in cellular metabolism, including signal transduction, membrane biosynthesis, and energy storage. These lipid phosphates are created through direct phosphorylation of lipids by lipid kinases such as diacylglycerol kinase and dolichol kinase which produce phosphatidic acid (PA) 1 and dolichyl monophosphate (dolichyl-P), respectively. Alternatively, these molecules can be formed by degradation of precursor molecules as in the hydrolysis of phospholipids by phospholipase D to form PA or the transfer of oligosaccharides from a dolichol carrier to produce dolichyl pyrophosphate (dolichyl-P-P) or dolichyl-P (1). The phosphorylated lipids can be metabolized by several phosphatases or used in synthetic reactions to produce a variety of phospholipids or dolichyl oligosaccharides (2-6).

Efficient Use of Exogenous Isoprenols for Protein Isoprenylation by MDA-MB-231 Cells Is Regulated Independently of the Mevalonate Pathway

“…In particular, we and others have described phosphatase activities and identified at least one integral membrane enzyme that can dephosphorylate FPP and GGPP. In support of this idea, manipulation of the expression of this enzyme modulates protein isoprenylation in cultured cells (2,24). Although a more expansive comparison of cells and tissues is clearly warranted, our study also suggests that there are significant differences in the efficiency with which different cultured mammalian cell lines metabolize exogenous isoprenols.…”

Identification and Functional Characterization of a Presqualene Diphosphate Phosphatase

“…1D). Type 2 phosphatidic acid phosphohydrolase (PAP2) isoenzymes are ϳ35 kDa, involved in lipid signaling, and can dephosphorylate FDP (16). To determine whether isoforms of PAP2 also displayed PSDP phosphatase activity, we first expressed human PAP2a and incubated recombinant protein (30 min, 37°C) with PSDP, PA (C10:0), FDP, and DGPP (C18:1)(10 M).…”

Purification, characterization, and bioinformatics studies of phosphatidic acid phosphohydrolase from <i>Lagenaria siceraria</i>

“…Type I PAPs are Mg 2+ -dependent and are often found distributed between cytosolic and membrane fractions. Type II PAPs seem to play no role in bulk cellular lipid metabolism, but are likely involved in signal transduction pathways [17,22,23]. Type I enzymes on the other hand, have been implicated in a direct role in phospholipid and triacylglycerol synthesis in yeast [6] and phospholipid and galactolipid synthesis in plants [18][19][20].…”

“…PAP activities are found in both the cytosolic and membrane fractions of yeast [6,17] and plants [18][19][20][21]. Type II PAPs are Mg 2+ -independent integral membrane proteins.…”