The Biosynthesis of Trehalose in Moniliformis dubius (Acanthocephala)

Abstract

The occurrence, distribution, and synthesis of the nonreducing disaccharide, trehalose, were investigated in the tissues of female Moniliformis dubius, an acanthocephalan parasite of the rat. It was found that, although the sugar was present in large quantity in the body fluid and acanthors in all stages of development, the enzymes responsible for synthesis could not be detected. A survey of the trehalose concentration in whole worms of various ages showed the pool levels in unstarved worms to be high and rather constant regardless of infection age. The enzymes of trehalose synthesis were located in the body wall of adult female worms. The pathway was found to resemble closely that described in yeast and insects; the enzyme has a specific requirement for uridine diphosphoglucose and glucose-6-phosphate as cosubstrates. There was an absolute requirement for divalent ions and trehalose inhibited its own synthesis. The formation of trehalose-6-phosphate, although never demonstrated, was presumed to occur. The biosynthesis of trehalose [1-(a-D-glucopyranosyl)-a-D-glucopyranoside] was first demonstrated in yeast (Cabib and Leloir, 1958). These workers showed that the pathways involved two enzymes: (1) Trehalose phosphate synthetase: UDPGt + Glucose-6-P -> UDP + Trehalose-6-P (2) Trehalose-6-phosphatase: Trehalose-6-P + H20 -> Trehalose + Pi The biosynthesis of trehalose was subsequently shown to proceed by a similar pathway in insect fat body (Candy and Kilby, 1961); this same reaction was later found to occur in other systems (Goldman and Lornitzo, 1962; Received for publication 20 May 1971. * This work supported by grants from the NIH (GM12263, 2 T01 AI00106) and the Robert A. Welch Foundation (C-239). t Present address: Department of Medical Zoology, Division of Communicable Diseases and Immunology, Walter Reed Army Institute of Research, Walter Reed Army Medical Center, Washington, D. C. 20012. t The following abbreviations are used: ATP for adenosine-5'-triphosphate, UDPG for uridine diphosphoglucose, GDPG for guanosine diphosphoglucose, ADPG for adenosine diphosphoglucose, CDPG for cytidine diphosphoglucose, TDPG for thymidine diphosphoglucose, EDTA for ethylene-diaminetetraacetic acid, Tris for Tris(hydroxymethyl) amino-methane, TM for Tris-maleate buffer, and KRT for Tris-buffered Krebs-Ringer's saline, pH 7.4. Roth and Sussman, 1966). Elbein (1967) demonstrated that GDPG was involved in the synthesis of trehalose-phosphate in Streptomyces hygroscopicus: GDPG + Glucose-6-P -> Trehalose-6-P GDP. This reaction has subsequently been shown to occur in a number of other species of Streptomyces (Elbein, 1968). More recently Liu et al. (1969) demonstrated that several species of Mycobacterium have the capacity to synthesize the disaccharide phosphate using either UDPG or GDPG as a precursor. It was futher shown that GDPG is the normal glucosyl donor for the synthesis of trehalose in Mycobacterium smegmatis, but in the presence of a polynucleotide fraction, the enzyme can be modified to utilize UDPG. Fairbairn (1958) reported trehalose to be present in 71 species of invertebrates representing the major phyla. One of the species examined was Moniliformis dubius, which was found to contain trehalose in a concentration of 2.3% of total tissue solids. Fairbairn speculated that trehalose would eventually be accepted as a carbohydrate occurring widely in invertebrates. Fairbairn and Passey (1957) examined the occurrence and distribution of trehalose and glycogen in the eggs of Ascaris suum. The egg glycogen was almost entirely concentrated in the embryo proper, while most of the trehalose was confined to the perivitelline