The sedoheptulose kinase CARKL directs macrophage polarization through control of glucose metabolism

Immune cells are somewhat unique in that activation responses can alter quantitative phenotypes upwards of 100,000-fold. To date little is known about the metabolic adaptations necessary to mount such dramatic phenotypic shifts. Screening for novel regulators of macrophage activation, we found nonprotein kinases of glucose metabolism among the most enriched classes of candidate immune modulators. We find that one of these, the carbohydrate kinase-like protein CARKL, is rapidly downregulated in vitro and in vivo upon LPS stimulation in both mice and humans. Interestingly, CARKL catalyzes an orphan reaction in the pentose phosphate pathway, refocusing cellular metabolism to a high-redox state upon physiological or artificial downregulation. We find that CARKL-dependent metabolic reprogramming is required for proper M1- and M2-like macrophage polarization and uncover a rate-limiting requirement for appropriate glucose flux in macrophage polarization.     

Synthesis of regioselectively sulfated xylodextrins and crystal structure of sodium methyl beta-D-xylopyranoside 4-O-sulfate hemihydrate

Methyl xylobioside and methyl xylotrioside were prepared from the peracetylated anomeric xylosyl trichloroacetimidates by reaction with methanol followed by Zemplén deacetylation. Methyl beta-D-xylopyranoside, methyl beta-D-xylobioside and methyl beta-D-xylotrioside were subjected to treatment with dibutyltin oxide followed by reaction with the trimethylamine/sulfur trioxide complex in tetrahydrofuran. This way, preferential sulfation of the terminal 4-hydroxy group at the nonreducing xylopyranosyl unit was achieved. In addition, partial sulfation at position 2 of the distal xylose unit was observed. The substitution pattern was derived from NMR spectroscopic data and was confirmed by the X-ray structure determination of sodium methyl beta-D-xylopyranoside 4-O-sulfate. The compound crystallized as a hemihydrate in a triclinic lattice of space group P1 and possesses a pseudomonoclinic 2D supramolecular structure. The sulfation of free pentose oligomers via their intermediate stannylene acetals may thus be exploited to generate biologically active oligosaccharides for biomedical applications.     

Biosynthesis pathway of ADP-L-glycero-beta-D-manno-heptose in Escherichia coli.

The steps involved in the biosynthesis of the ADP-L-glycero-beta-D-manno-heptose (ADP-L-beta-D-heptose) precursor of the inner core lipopolysaccharide (LPS) have not been completely elucidated. In this work, we have purified the enzymes involved in catalyzing the intermediate steps leading to the synthesis of ADP-D-beta-D-heptose and have biochemically characterized the reaction products by high-performance anion-exchange chromatography. We have also constructed a deletion in a novel gene, gmhB (formerly yaeD), which results in the formation of an altered LPS core. This mutation confirms that the GmhB protein is required for the formation of ADP-D-beta-D-heptose. Our results demonstrate that the synthesis of ADP-D-beta-D-heptose in Escherichia coli requires three proteins, GmhA (sedoheptulose 7-phosphate isomerase), HldE (bifunctional D-beta-D-heptose 7-phosphate kinase/D-beta-D-heptose 1-phosphate adenylyltransferase), and GmhB (D,D-heptose 1,7-bisphosphate phosphatase), as well as ATP and the ketose phosphate precursor sedoheptulose 7-phosphate. A previously characterized epimerase, formerly named WaaD (RfaD) and now renamed HldD, completes the pathway to form the ADP-L-beta-D-heptose precursor utilized in the assembly of inner core LPS.     

Biosynthesis of dTDP-3-acetamido-3,6-dideoxy-alpha-D-glucose

Derivatives of 3-amino-3,6-dideoxyhexoses are widespread in Nature. They are part of the repeating units of lipopolysaccharide O-antigens, of the glycan moiety of S-layer (bacterial cell surface layer) glycoproteins and also of many antibiotics. In the present study, we focused on the elucidation of the biosynthesis pathway of dTDP-alpha-D-Quip3NAc (dTDP-3-acetamido-3,6-dideoxy-alpha-D-glucose) from the Gram-positive, anaerobic, thermophilic organism Thermoanaerobacterium thermosaccharolyticum E207-71, which carries Quip3NAc in its S-layer glycan. The biosynthesis of dTDP-alpha-D-Quip3NAc involves five enzymes, namely a transferase, a dehydratase, an isomerase, a transaminase and a transacetylase, and follows a pathway similar to that of dTDP-alpha-D-Fucp3NAc (dTDP-3-acetamido-3,6-dideoxy-alpha-D-galactose) biosynthesis in Aneurinibacillus thermoaerophilus L420-91(T). The ORFs (open reading frames) of interest were cloned, overexpressed in Escherichia coli and purified. To elucidate the enzymatic cascade, the different products were purified by HPLC and characterized by NMR spectroscopy. The initiating reactions catalysed by the glucose-1-phosphate thymidylyltransferase RmlA and the dTDP-D-glucose-4,6-dehydratase RmlB are well established. The subsequent isomerase was shown to be capable of forming a dTDP-3-oxo-6-deoxy-D-glucose intermediate from the RmlB product dTDP-4-oxo-6-deoxy-D-glucose, whereas the isomerase involved in the dTDP-alpha-D-Fucp3NAc pathway synthesizes dTDP-3-oxo-6-deoxy-D-galactose. The subsequent reaction steps of either pathway involve a transaminase and a transacetylase, leading to the specific production of nucleotide-activated 3-acetamido-3,6-dideoxy-alpha-D-glucose and 3-acetamido-3,6-dideoxy-alpha-D-galactose respectively. Sequence comparison of the ORFs responsible for the biosynthesis of dTDP-alpha-D-Quip3NAc revealed homologues in Gram-negative as well as in antibiotic-producing Gram-positive bacteria. There is strong evidence that the elucidated biosynthesis pathway may also be valid for LPS (lipopolysaccharide) O-antigen structures and antibiotic precursors.     

Increased expression of matrix metalloproteinase-2 (MMP-2) predicts tumour recurrence and unfavourable outcome in non-small cell lung cancer

The purpose of this study was to analyse the expression of matrix metalloproteinase-2 (MMP-2) and its extracellular matrix metalloproteinase inducer (EMMPRIN) in non-small cell lung cancer (NSCLC), and to evaluate their significance to predict tumour behaviour. The study consists of 212 patients treated by the resection of the tumour. Tumour samples were stained immunohistochemically, and the expression of MMP-2 and EMMPRIN was evaluated both in tumour cells and in peritumoural stromal tissue. The results were compared with clinicopathological factors and survival of the patients. High expression of MMP-2 in tumour cells was found in 83 out of 191 cases (44%). Adenocarcinomas showed more often high expression of MMP-2 as compared with squamous cell or large cell carcinomas (p=0.001). High cancer cell associated MMP-2 expression was associated with increased tumour recurrence (p=0.001). Tumour stroma showed positive staining in 162 (98%) cases and was considered highly stained in 120 (72%) cases. The high stromal MMP-2 expression was noticed more often among large cell carcinomas as compared with other histological types (p=0.007). High cancer cell associated EMMPRIN expression was found in 115 (61%) cases and was associated only with high MMP-2 expression in tumour cells (p=0.006). In overall survival (OS) and disease free survival (DFS) analyses, type of tumour (p=0.001 and p=0.0004), advanced stage (p=0.001 and p=0.013) and high MMP-2 expression in tumour cells (p=0.018 and p=0.001) were associated with poor survival. Also, high stromal MMP-2 expression was related to poor outcome in both OS and DFS analyses (p=0.010 and 0.045, respectively). In multivariate analysis, stromal MMP-2 expression retained its prognostic value to predict OS and DFS (p=0.028 and p=0.039, respectively), together with tumour type and stage (p=0.017, p=0.001 and p=0.021, p=0.008, respectively). The present study shows the significant prognostic value of MMP-2 in NSCLC suggesting that the use of MMP-2 is valuable in determining the patients with more aggressive disease.     

Purification and structure elucidation of the N-acetylbacillosamine-containing polysaccharide from Bacillus licheniformis ATCC 9945.

The exopolysaccharide of Bacillus licheniformis ATCC 9945 (formerly B. subtilis ATCC 9945) contains among other glycoses 4-acetamido-2-amino-2,4,6-trideoxy-D-glucose, termed N-acetylbacillosamine (Bac2N4NAc). A similar diamino glycose, 2-acetamido-4-amino-2,4,6-trideoxy-D-glucose, was found in a surface layer (S-layer) glycoprotein preparation of Clostridium symbiosum HB25. Electron microscopic studies, however, showed that B. licheniformis ATCC 9945 is not covered with an S-layer lattice, indicating that the N-acetylbacillosamine present in that organism might be a constituent of a cell wall-associated polymer. For elucidation of the structure of the N-acetylbacillosamine-containing polysaccharide, it was purified from a trichloroacetic acid extract of B. licheniformis ATCC 9945 cells. Using different hydrolysis protocols and a hydrolysate of the S-layer glycoprotein preparation from C. symbiosum HB25 as reference, the purified polysaccharide was found to contain 2,4-diamino-2,4,6-trideoxy-glucose, 2-acetamido-2-deoxy-glucose, 2-acetamido-2-deoxy-galactose and galactose in a molar ratio of 1 : 1 : 1 : 2. One- and two-dimensional NMR spectroscopy, including 800 MHz proton magnetic resonance measurements, in combination with chemical modification and degradation experiments, revealed that the polysaccharide consists of identical pyruvylated pentasaccharide repeating units with the structure: [-->3)-[(S)Py-(3,4)-beta-D-Galp-(1-->6)]-alpha-D-GlcpNAc-(1-->3)-beta-D-Bacp2N4NAc-(1-->3)-[(S)Py-(3,4)-beta-D-Galp-(1-->6)]-beta-D-GalpNAc-(1-->](n)     

Synthesis of neoglycoproteins containing D-glycero-D-talo-oct-2-ulopyranosylonic acid (Ko) ligands corresponding to core units from Burkholderia and Acinetobacter lipopolysaccharide

Glycal esters of Kdo derivatives were converted into 2,3-anhydro intermediates, which were transformed into D-glycero-D-talo-oct-2-ulopyranosylonic acid (Ko), as well as 3-O- and 4-O-p-nitrobenzoyl-Ko derivatives. The exo-allyl orthoester derivative, methyl [5,7,8-tri-O-acetyl-4-O-(4-nitrobenzoyl)-2,3-O-[(1-exo-allyloxy)-ethylidene]-D-glycero-beta-D-talo-oct-2-ulopyranos]onate, prepared from the 4-O-pNBz-protected Ko derivative, was elaborated into the alpha-Ko allyl ketoside, the reducing disaccharide alpha-Kdop-(2-->4)-Ko and the disaccharide alpha-Kdop-(2-->4)-Kop-(2-->OAll). Conversely, methyl[4,5,7,8-tetra-O-acetyl-3-O-(4-nitrobenzoyl)-alpha-D-glycero-D-talo-2-octulopyranosyl bromide]onate [Carbohydr. Res., 244 (1993) 69-84], was coupled with a Kdo acceptor to give the disaccharide alpha-Kop-(2-->4)-Kdop-(2-->OAll) after orthoester rearrangement and deprotection. The allyl glycosides were treated with cysteamine and converted into neoglycoproteins. The ligands correspond to inner core units from Acinetobacter haemolyticus and Burkholderia cepacia lipopolysaccharides.     

Kinetic and chemical studies on the isomerization of monosaccharides in N-methylmorpholine-N-oxide (NMMO) under Lyocell conditions

The Lyocell process is a modern and environmentally fully compatible industrial fiber-making technology. Cellulosic pulp is dissolved without chemical derivatization in a melt of N-methylmorpholine-N-oxide monohydrate (NMMO). In the present work, the reactions of monosaccharides under Lyocell conditions were investigated in detail, using capillary zone electrophoresis as the analytical technique to clarify the composition of reaction mixtures and to follow the kinetics. Under Lyocell conditions, xylose and glucose undergo two competitive reactions: rapid conversion to nonreducing products, and complete isomerization involving the whole carbohydrate backbone, via ketose intermediates. Sugar acids are present in minor amounts only, as demonstrated by employing isotopically labeled material for NMR techniques.     

A convenient synthesis of GDP D-glycero-alpha-D-manno-heptopyranose

GDP D-glycero-alpha-D-manno-Heptopyranose has been prepared in good overall yield from 2,3,4,6,7-penta-O-acetyl-D-glycero-D-manno-heptopyranose by a short-step synthesis. Phosphitylation using the phosphoramidite procedure afforded the alpha-anomer in high selectivity. Subsequent oxidation and partial deprotection gave the acetylated phosphate derivative, which was subjected to the coupling reaction with GMP-morpholidate to furnish the acetylated heptose nucleoside diphosphate in good yield. De-O-acetylation and final purification afforded the target GDP D-glycero-alpha-D-manno-heptopyranose, which serves as the substrate of the heptosyl transferase in Aneurinibacillus thermoaerophilus DSM 10155 and occurs as an intermediate in the biosynthesis of GDP 6-deoxy-heptose in Yersinia pseudotuberculosis.     

Crystal and molecular structure of methyl 4-O-methyl-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranoside

The cellulose model compound methyl 4-O-methyl-beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranoside (6) was synthesised in high overall yield from methyl beta-D-cellobioside. The compound was crystallised from methanol to give colourless prisms, and the crystal structure was determined. The monoclinic space group is P2(1) with Z=2 and unit cell parameters a=6.6060 (13), b=14.074 (3), c=9.3180 (19) A, beta=108.95(3) degrees. The structure was solved by direct methods and refined to R=0.0286 for 2528 reflections. Both glucopyranoses occur in the 4C(1) chair conformation with endocyclic bond angles in the range of standard values. The relative orientation of both units described by the interglycosidic torsional angles [phi (O-5' [bond] C-1' [bond] O-4 [bond] C-4) -89.1 degrees, Phi (C-1' [bond] O-4 [bond] C-4 [bond] C-5) -152.0 degrees] is responsible for the very flat shape of the molecule and is similar to those found in other cellodextrins. Different rotamers at the exocyclic hydroxymethyl group for both units are present. The hydroxymethyl group of the terminal glucose moiety displays a gauche-trans orientation, whereas the side chain of the reducing unit occurs in a gauche-gauche conformation. The solid state (13)C NMR spectrum of compound 6 exhibits all 14 carbon resonances. By using different cross polarisation times, the resonances of the two methyl groups and C-6 carbons can easily be distinguished. Distinct differences of the C-1 and C-4 chemical shifts in the solid and liquid states are found.