Studies on trehalose phosphate synthetase in Mycobacterium smegmatis

[摘要] The biosynthesis of trehalose phosphate occurs by two reactions which utilize different sugar nucleotides, UDP-glucose or GDP-glucose. Cell free extracts of several mycobacteria catalyzed the synthesis of trehalose phosphate from both UDPglucose and GDP-glucose. An extract of Mycobacterium smegmatis was separated into two fractions by chromatography on DEAE cellulose. Fraction 1 catalyzed the synthesis of trehalose (trehalose-P) from GDP-glucose but only slightly active with UDP-glucose. However, when fraction 2 was added to fraction 1, UDP-glucose was able to serve as an effective glucosyl donor for trehalose synthesis. Under these conditions, GDP-glucose was still active. Fraction 2 had no detectable enzymatic activity and was heat-stable. The action of fraction 2 could be replaced by crude a -lactalbumin, but not by pure a -lactalbumin, lysozyme, albumin or a number of other proteins. The products formed from UDP-glucose-14C and fractions 1 and 2 or GDP-glucose-14C and fraction' 1 were identified as trehalose by paper chromatography and cocrystallization of the octaacetate derivative to constant specific activity with authentic trehalose octaacetate.As to the substrate specificity, ADP-glucose gave similar results to UDP-glucose. Fructose-6-P was equally effective in fulfilling the requirement for glucose-6-P, presumably due to the presence of phosphohexose isomerase.

[发布机构] Rice University