Distribution of glucose incorporated into macromolecular material by treponema pallidum

Abstract

Treponema pallidum was observed to incorporate glucose carbons into lipids, ribonucleic acid, deoxyribonucleic acid, and protein. Only the glycerol portions of phosphatidylcholine and phosphatidylglycerol contained glucose-derived carbons. Incorporation of exogenous choline into phosphatidylcholine was detected. Glucose was incorporated into only the pentoses of nucleic acids. About 50% of the glucose incorporated into protein was present in only one amino acid, aspartate. Evidence suggests that aspartate synthesis could follow the conversion of phosphoenolpyruvate to oxalacetic acid by a guanosine 5'-diphosphate-dependent phosphoenolpyruvate carboxykinase. Treponemapallidum degrades glucose via the Embden-Meyerhof and hexose monophosphate pathways (37), producing C02, acetate, pyruvate, and lactate (7). Nicotinamide adenine dinucleotide (NAD)-dependent lactate dehydrogenase catalyzes the reduction of pyruvate to lactate (37), whereas an oxidase, similar to the pyruvate oxidase of Lactobacillus delbruckii, catalyzes the oxidation of pyruvate to C02 and acetylphosphate (4). Glucose catabolism appears to be coupled to energy generation through both substrate-level (4, 37) and oxidative phosphorylation (26). Recently, T. pallidum has been shown to incorporate glucose into trichloroacetic acid-precipitable material (3). The purpose of this study was to determine the fate of glucose carbons incorporated into macromolecular components. MATERIALS AND METHODS Preparation of treponeme suspensions. Propagation, extraction, purification, and counting of the Nichols strain of virulent T. pallidum have been described (4, 26, 37). Extraction of treponemes from infected testicles was performed for 1 h at room temperature in a maintenance medium (BME) containing 34.0 mM NaCl, 5.4 mM KCI, 0.4 mM MgSO4, 0.34 mM CaCl12, 10.0 mM MOPS (morpholinopropanesulfonic acid), 10.0 mM TES [N-tris(hydroxymethyl)methyl-2aminoethanesulfonic acid], 15 mM HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid), 3.0 ,M thiamine hydrochloride, 0.015 ,uM vitamin B12, 0.4 ,M biotin, 0.4 ,uM p-amino-benzoic acid, 0.2 AM nicotinamide, 0.1 MM pyridoxine hydrochloride, 0.2 ,M folic acid, 4.5 AM calcium pantothenate, 10.0 yM Na2HPO4, 0.08 mM ornithine, 0.02 mM NAD, 16.0 mM NaHCO3, 0.2% bovine serum albumin, and 10.0 mM reduced glutathione, at a final pH of 7.4. Testicular suspensions were shaken under atmospheric 02 tensions for 1 h at room temperature and 1 h at 4°C.

Evidence for a methyl-accepting chemotaxis protein gene (mcp1) that encodes a putative sensory transducer in virulent Treponema pallidum

“…Glucose is believed to be the principal carbon and energy source for T. pallidum (3,47,58). T. pallidum Mcp1 described herein, combined with the recognition in T. pallidum of a complete mgl operon (51,65), cheA (17), cheW (17), and the importance of endoflagellar rotation in treponemal motility (10), allows us to propose a model for treponemal chemotaxis based upon glucose utilization.…”

A CDP‐choline pathway for phosphatidylcholine biosynthesis in Treponema denticola

“…Several species of Treponema , including T. denticola , have been reported to contain PC and several other phospholipids including PE and PG (Livermore and Johnson, 1974; Smibert, 1976; Barbieri et al ., 1981), but the amount of each phospholipid in T. denticola has not previously been reported quantitatively. In order to confirm the presence of and measure the amount of PC in T. denticola , total lipids were extracted and chromatographed by thin‐layer chromatography in several different solvent systems.…”

“…The licCA ‐containing organisms include Treponema pallidum , which causes syphilis, Fusobacterium nucleatum , which is involved in periodontal disease, and Clostridium perfringens , which causes gangrene. Although little information is available on phospholipid synthesis and composition in fusobacteria and clostridia, it is of interest that the treponemes have been reported to contain PC as a major membrane phospholipid (Livermore and Johnson, 1974; Matthews et al ., 1979; Barbieri et al ., 1981; Belisle et al ., 1994). The presence of the licCA fusion gene in treponemes suggests that they may utilize a CDP‐choline pathway for biosynthesis of PC.…”

The Tp0684 (MglB-2) Lipoprotein of Treponema pallidum: A Glucose-Binding Protein with Divergent Topology

“…pallidum is thought to be microaerophilic[ 65 ], and there is no evidence that the electron-transport chain that would allow canonical aerobic respiration exists in the organism [ 30 ]. Further, D-glucose is believed to be the main, if not sole, carbon source for the microorganism [ 32 – 35 ]. Thus, a modified glycolytic pathway could be the only means for energy generation in T .…”

“…For T . pallidum , the preferred energy source likely is glucose [ 32 – 35 ], as this monosaccharide is more abundant in human plasma than alternative carbon sources [ 36 ], and the spirochete contains all of the necessary enzymes for glycolysis [ 30 ]. Further, the organism probably has a means for the conversion of reducing equivalents from glycolysis to electrochemical potentials that can be utilized for further ATP generation [ 28 ].…”