The LPP1 and DPP1 gene products account for most of the isoprenoid phosphate phosphatase activities in Saccharomyces cerevisiae

Two genes in Saccharomyces cerevisiae, LPP1 and DPP1, with homology to a ma mmalian phosphatidic acid (PA) phosphatase were identified and disrupted. N either single nor combined deletions resulted in growth or secretion phenot ypes. As observed previously (Toke, D. A., Bennett, W. L., Dillon, D. A., W u, W.-I., Chen, X., Ostrander, D. B., Oshiro, J., Cremesti, A., Voelker, D. R., Fischl, A. S., and Carman, G. M. (1998) J. Biol. Chem. 273, 3278-3284; Toke, D. A., Bennett, W. L., Oshiro, J., Wu, W.-I., Voelker, D. R., and Ca rman, G. M. (1998) J. Biol. Chem. 273, 14331-14338), the disruption of DPP1 and LPP1 produced profound losses of Mg2+-independent PA phosphatase activ ity. The coincident attenuation of hydrolytic activity against diacylglycer ol pyrophosphate prompted an examination of the effects of these disruption s on hydrolysis of isoprenoid pyrophosphates. Disruption of either LPP1 or DPP1 caused respective decreases of about 25 and 75% in Mg2+-independent hy drolysis of several isoprenoid phosphates by particulate fractions isolated from these cells. The particulate and cytosolic fractions from the double disruption (lpp1 Delta dpp1 Delta) showed essentially complete loss of Mg2-independent hydrolytic activity toward dolichyl phosphate (dolichyl-P), do lichyl pyrophosphate (dolichyl-P-P), farnesyl pyrophosphate (farnesyl-P-P), and geranylgeranyl pyrophosphate (geranylgeranyl-P-P). However, a modest M g2+-stimulated activity toward PA and dolichyl-P was retained in cytosol fr om lpp1 Delta dpp1 Delta cells. The action of Dpp1p on isoprenyl pyrophosph ates was confirmed by characterization of the hydrolysis of geranylgeranyl- P-P by the purified protein. These results indicate that LPP1 and DPP1 acco unt 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 ot her enzymes capable of dephosphorylating these essential isoprenoid interme diates.