Enzymatic Formation of Dehydrodolichal and Dolichal, New Products Related to Yeast Dolichol Biosynthesis

Abstract

Two new polyprenyl products in addition to dehydrodolichol and dolichol were detected by two-plate silica gel thin layer chromatography of nonpolar products formed from [1-14C]isopentenyl diphosphate and farnesyl diphosphate in the reaction with a crude 1,000 x g supernatant of yeast homogenates in the presence of NADPH. The new products were indistinguishable from authentic dehydrodolichal and dolichal. Analyses of the time-dependent and pH-dependent formation of the four products including dehydrodolichal and dolichal suggested that the biosynthetic pathway from dehydrodolichol leading to dolichal is different from that to dolichol. In double-labeled experiments with a combination of -l-14C-isopentenyl diphosphate and a [4B-3H]NADPH-generating system, the ratio of 3H- and 14C-derived radioactivities found in dolichal was six times higher than that in dolichol. A small amount of 3H-labeled dehydrodolichol was also detected. Considering the fact that dolichol is synthesized from dehydrodolichol (Sagami, H., Kurisaki, A., and Ogura, K. (1993) J. Biol. Chem. 268, 10109-10113), we propose that dehydrodolichol is a common branch point intermediate in the biosynthetic pathways leading to dolichal and dolichol and that dehydrodolichal is an intermediate in the pathway from dehydrodolichol to dolichal.

Quantitation by1H-NMR of dolichol, cholesterol and choline-containing lipids in extracts of normal and phathological thyroid tissue

“…38 Therefore, further analytical studies with separation of the isoprenoids are needed to obtain more precise information about specific dolichol species in the thyroid organ.…”

SRD5A3 Is Required for Converting Polyprenol to Dolichol and Is Mutated in a Congenital Glycosylation Disorder

“…The alpha-isoprene unit of the polyprenol is subsequently reduced by an NADPH-dependent microsomal reductase. For this step, the corresponding aldehydes have also been suggested as intermediates (Sagami et al, 1996). Finally the dolichol-specific kinase (SEC59/DK) transfers a phosphate from CTP to dolichol.…”

Conservation of the PTEN catalytic motif in the bacterial undecaprenyl pyrophosphate phosphatase, BacA/UppP

“…However, based on [ 3 H]mevalonate labelling studies in membrane fractions, Ekström et al (1987) proposed that terminal isoprene condensation and a-saturation occur cooperatively. A third plausible model is based on dehydrodolichol reductase activity in microsomal fractions that achieves a-isoprene saturation preceded by a dephosphorylation of dehydro-Dol-PP (Sagami et al, 1993(Sagami et al, , 1996.…”