Distribution of thiols in microorganisms: mycothiol is a major thiol in most actinomycetes

Mycothiol [2-(N-acetylcysteinyl)amido-2-deoxy-alpha-D-glucopyranosyl- (1-->1)-myo-inositol] (MSH) has recently been identified as a major thiol in a number of actinomycetes (S. Sakuda, Z.-Y. Zhou, and Y. Yamada, Biosci. Biotech. Biochem. 58:1347-1348, 1994; H. S. C. Spies and D. J. Steenkamp, Eur. J. Biochem. 224:203-213, 1994; and G. L. Newton, C. A. Bewley, T. J. Dwyer, R. Horn, Y. Aharonowitz, G. Cohen, J. Davies, D. J. Faulkner, and R. C. Fahey, Eur. J. Biochem. 230:821-825, 1995). Since this novel thiol is more resistant than glutathione to heavy-metal ion-catalyzed oxidation, it seems likely to be the antioxidant thiol used by aerobic gram-positive bacteria that do not produce glutathione (GSH). In the present study we sought to define the spectrum of organisms that produce MSH. GSH was absent in all actinomycetes and some of the other gram-positive bacteria studied. Surprisingly, the streptococci and enterococci contained GSH, and some strains appeared to synthesize it rather than import it from the growth medium. MSH was found at significant levels in most actinomycetes examined. Among the actinobacteria four Micrococcus species produced MSH, but MSH was not found in representatives of the Arthrobacter, Agromyces, or Actinomyces genera. Of the nocardioforms examined, Nocardia, Rhodococcus, and Mycobacteria spp. all produced MSH. In addition to the established production of MSH by streptomycetes, we found that Micromonospora, Actinomadura, and Nocardiopsis spp. also synthesized MSH. Mycothiol production was not detected in Propionibacterium acnes or in representative species of the Listeria, Staphylococcus, Streptococcus, Enterococcus, Bacillus, and Clostridium genera. Examination of representatives of the cyanobacteria, purple bacteria, and spirochetes also gave negative results, as did tests of rat liver, bonito, Candida albicans, Neurospora crassa, and spinach leaves. The results, which indicate that MSH production is restricted to the actinomycetes, could have significant implications for the detection and treatment of infections with actinomycetes, especially those caused by mycobacteria.

Composition of perineuronal net extracellular matrix in rat brain: a different disaccharide composition for the net-associated proteoglycans

We developed a method to extract differentially chondroitin sulfate proteoglycans (CSPGs) that are diffusely present in the central nervous system (CNS) matrix and CSPGs that are present in the condensed matrix of perineuronal nets (PNNs). Adult rat brain was sequentially extracted with Tris-buffered saline (TBS), TBS-containing detergent, 1 m NaCl, and 6 m urea. Extracting tissue sections with these buffers showed that the diffuse and membrane-bound CSPGs were extracted in the first three buffers, but PNN-associated CSPGs remained and were only removed by 6 m urea. Most of the CSPGs were extracted to some degree with all the buffers, with neurocan, brevican, aggrecan, and versican particularly associated with the stable urea-extractable PNNs. The CSPGs in stable complexes only extractable in urea buffer are found from postnatal day 7-14 coinciding with PNN formation. Disaccharide composition analysis indicated a different glycosaminoglycan (GAG) composition for PGs strongly associated with extracellular matrix (ECM). For CS/dermatan sulfate (DS)-GAG the content of nonsulfated, 6-O-sulfated, 2,6-O-disulfated, and 4,6-O-disulfated disaccharides were higher and for heparan sulfate (HS)-GAG, the content of 6-O-sulfated, 2-N-, 6-O-disulfated, 2-O-, 2-N-disulfated, and 2-O-, 2-N-, 6-O-trisulfated disaccharides were higher in urea extract compared with other buffer extracts. Digestions with chondroitinase ABC and hyaluronidase indicated that aggrecan, versican, neurocan, brevican, and phosphacan are retained in PNNs through binding to hyaluronan (HA). A comparison of the brain and spinal cord ECM with respect to CSPGs indicated that the PNNs in both parts of the CNS have the same composition.

Oocyte Gal alpha 1,3Gal epitopes implicated in sperm adhesion to the zona pellucida glycoprotein ZP3 are not required for fertilization in the mouse

The Gal alpha 1-->3Gal structure is displayed on the zona pellucida glycoprotein ZP3 on murine oocytes. This trisaccharide has been implicated in sperm-zona pellucida adhesive events thought to be essential to fertilization in the mouse. To determine directly if this molecule is required for fertilization, we have generated mice that are deficient in a gene (alpha 1,3GT) encoding the UDP-Gal:beta-D-Gal-alpha 1-->3Gal-galactosyltransferase enzyme responsible for Gal alpha 1-->3Gal synthesis and expression. These mice develop normally and exhibit no gross phenotypic abnormalities. The Gal alpha 1-->3Gal epitope is absent from the vascular endothelium and other tissues in alpha 1,3GT (-/-) adult mice. By contrast, alpha 1,3GT (-/-) mice, like humans, develop naturally occurring anti-alpha-galactoside antibodies normally absent in wild type mice. Female alpha 1,3GT (-/-) mice yield oocytes that are devoid of the Gal alpha 1-->3Gal epitope; however, these mice are fully fertile. These observations indicate that the Gal alpha 1-->3Gal moiety is not essential to sperm-oocyte interactions leading to fertilization or to essentially normal development. They further suggest that alpha 1,3GT (-/-) mice will find utility for exploring approaches to diminish anti-Gal-dependent hyperacute xenograft rejection, which presents a major barrier to the use of porcine and other non-primate organs for xenotransplantation in humans.

Polyphosphate kinase is essential for biofilm development, quorum sensing, and virulence of Pseudomonas aeruginosa

The human opportunistic pathogen Pseudomonas aeruginosa causes a variety of infections in immunocompromised hosts and in individuals with cystic fibrosis. A knockout mutation in the polyphosphate kinase (ppk) gene, encoding PPK responsible for the synthesis of inorganic polyphosphate from ATP, renders P. aeruginosa cells unable to form a thick and differentiated biofilm. The mutant is aberrant in quorum sensing and responses in that production of the quorum-sensing controlled virulence factors elastase and rhamnolipid are severely reduced. In a burned-mouse pathogenesis model, the virulence of the mutant is greatly reduced with severe defects in the colonization of mouse tissues. The conservation of PPK among many bacterial pathogens and its absence in eukaryotes suggest that PPK might be an attractive target for antimicrobial drugs.

Rapid changes of heat and desiccation tolerance correlated with changes of trehalose content in Saccharomyces cerevisiae cells subjected to temperature shifts

The trehalose content of exponentially growing Saccharomyces cerevisiae cells rapidly increased in response to a temperature shift from 27 to 40 degrees C and decreased again when the temperature was shifted back from 40 to 27 degrees C. These changes were closely correlated with increases and decreases in the thermotolerance and desiccation tolerance of the cells. Our results support the hypothesis that trehalose functions as a protectant against heat and desiccation.

Phenolic components of the primary cell wall. Feruloylated disaccharides of D-galactose and L-arabinose from spinach polysaccharide

1. Cell walls from rapidly growing cell suspension cultures of Spinacia oleracea L. contained ferulic acid and p-coumaric acid esterified with a water-insoluble polymer. 2. Prolonged treatment with trypsin did not release may feruloyl esters from dearabinofuranosylated cell walls, and the polymer was also insoluble in phenol/acetic acid/water (2:1:1, w/v/v). 3. Treatment of the cell walls with the fungal hydrolase preparation "Driselase' did liberate low-Mr feruloyl esters. The major esters were 4-O-(6-O-feruloyl-beta-D-galactopyranosyl)-D-galactose and 3?-O-feruloyl-alpha-L-arabinopyranosyl)-L-arabinose. These two esters accounted for about 60% of the cell-wall ferulate. 4. It is concluded that the feruloylation of cell-wall polymers is not a random process, but occurs at very specific sites, probably on the arabinogalactan component of pectin. 5. The possible role of such phenolic substituents in cell-wall architecture and growth is discussed.

Microanalysis of glycosaminoglycan-derived oligosaccharides labeled with a fluorophore 2-aminobenzamide by high-performance liquid chromatography: application to disaccharide composition analysis and exosequencing of oligosaccharides

A series of disaccharides derived from chondroitin sulfate and heparin/heparan sulfate were derivatized at their reducing ends with a fluorophore 2-aminobenzamide to develop a sensitive microanalytical method for glycosaminoglycans. The resulting labeled compounds derived from chondroitin sulfate or heparin/heparan sulfate were well-separated and quantified by HPLC equipped with a fluorescence detector. The detection limit was a low picomole level. This method was applied to the analysis of the disaccharide composition of tetra- and hexasaccharides derived from chondroitin sulfate and heparin/heparan sulfate as well as these glycosaminoglycan polysaccharides. The method was also successfully applied to the exosequencing of chondrohexasaccharides, where the fluorophore-labeled oligosaccharides were degraded exolytically from the nonreducing ends using bacterial eliminases. The resultant labeled fragments were identified by HPLC.

Assay of intestinal disaccharidases

A modified and updated description of the author's method for the assay of intestinal disaccharidases. The principle of the method is the following: an intestinal homogenate is incubated with the appropriate disaccharide. The disaccharidase activity is then interrupted by the addition of TRIS, and the glucose liberated is measured with a glucose oxidase reagent.

Sulfation of chondroitin sulfate in human articular cartilage. The effect of age, topographical position, and zone of cartilage on tissue composition

The chondroitin ABC lyase digestion products of normal human femoral condyle articular cartilage and of purified aggrecan were analyzed for their mono- and nonsulfated disaccharide composition. Changes in the total tissue chemistry were most pronounced during the period from birth to 20 years of age, when the -[GlcAbeta,3GalNAc6]- disaccharide content increased from approximately 50% to 85% of the total disaccharide content and there was a concomitant decrease in the content of the 4-sulfated disaccharide. In general, the disaccharide content of the deeper layers of immature cartilage were richer in the 4-sulfated residue than the upper regions of the tissue. As the tissue aged and decreased in thickness, the disaccharide composition became more evenly 6-sulfated. The newly synthesized chondroitin sulfate chains had a similar composition to the endogenous chains and also underwent the same age and zonal changes. The monoclonal antisera 3B3(+) and 2B6(+) were used to immunolocalize the unsaturated 6- and 4-sulfated residues generated at the reducing termini of the chondroitin sulfate chains by digestion with chondroitin ABC lyase, and these analyses indicated that the sulfation pattern at this position did not necessarily reflect the internal disaccharide composition of the chains. In summary, the sulfation pattern of chondroitin sulfate disaccharides from human normal articular cartilage varies with the age of the specimen, the position (topography) on the joint surface, and the zone of cartilage analyzed. Furthermore, these changes in composition are a consequence of both extracellular, post-translational processing of the core protein of aggrecan and changes in the sulfotransferase activity of the chondrocyte.

Separation of sodiated isobaric disaccharides and trisaccharides using electrospray ionization-atmospheric pressure ion mobility-time of flight mass spectrometry

A series of isobaric disaccharide-alditols, four derived from O-linked glycoproteins, and select trisaccharides were rapidly resolved using tandem high resolution atmospheric pressure ion-mobility time-of-flight mass spectrometry. Electrospray ionization was used to create the gas-phase sodium adducts of each carbohydrate. Using this technique it was possible to separate up to three isobaric disaccharide alditols and three trisaccharides in the gas phase. Reduced mobility values and experimentally determined ion-neutral cross sections are reported for each sodium-carbohydrate complex. These studies demonstrated that ion mobility separations at atmospheric pressure can provide a high-resolution dimension for analysis of carbohydrate ions that is complementary to traditional mass spectral (m/z) ion analysis. Combining these independent principles for separation of ions provides a powerful new bioanalytical tool for the identification of isomeric carbohydrates.

Analysis of unsaturated disaccharides from glycosaminoglycuronan by high-performance liquid chromatography

A rapid and simple analytical method for unsaturated disaccharide isomers formed by enzymatic digestion from hyaluronic acid, chondroitin sulfate, dermatan sulfate, heparan sulfate, and heparin by high-performance liquid chromatography using an amine-bound silica column with a linear gradient of sodium dihydrogen phosphate was developed. The analyses were performed on isomers of two groups belonging to the chondroitin sulfate family and the heparin sulfate family. In both families, disaccharide isomers eluted in the order non-, mono-, di-, and trisulfated disaccharides by elevating salt concentrations. The method was applied to the analysis of constituent disaccharides of representative sulfated glycosaminoglycans, which proved that most constituents could be quantified separately. This method is advantageous in that enzymatic digests can be applied directly on a column without any pretreatment and good resolution of several disaccharides can be obtained by one chromatography.

Metabolic profiling during peach fruit development and ripening reveals the metabolic networks that underpin each developmental stage

Fruit from rosaceous species collectively display a great variety of flavors and textures as well as a generally high content of nutritionally beneficial metabolites. However, relatively little analysis of metabolic networks in rosaceous fruit has been reported. Among rosaceous species, peach (Prunus persica) has stone fruits composed of a juicy mesocarp and lignified endocarp. Here, peach mesocarp metabolic networks were studied across development using metabolomics and analysis of key regulatory enzymes. Principal component analysis of peach metabolic composition revealed clear metabolic shifts from early through late development stages and subsequently during postharvest ripening. Early developmental stages were characterized by a substantial decrease in protein abundance and high levels of bioactive polyphenols and amino acids, which are substrates for the phenylpropanoid and lignin pathways during stone hardening. Sucrose levels showed a large increase during development, reflecting translocation from the leaf, while the importance of galactinol and raffinose is also inferred. Our study further suggests that posttranscriptional mechanisms are key for metabolic regulation at early stages. In contrast to early developmental stages, a decrease in amino acid levels is coupled to an induction of transcripts encoding amino acid and organic acid catabolic enzymes during ripening. These data are consistent with the mobilization of amino acids to support respiration. In addition, sucrose cycling, suggested by the parallel increase of transcripts encoding sucrose degradative and synthetic enzymes, appears to operate during postharvest ripening. When taken together, these data highlight singular metabolic programs for peach development and may allow the identification of key factors related to agronomic traits of this important crop species.

Human glomerular basement membrane: chemical alteration in diabetes mellitus

The human glomerular basement membrane belongs to the collagen family of proteins. It contains about 7 percent carbohydrate, half of which occurs as glucosylgalactose disaccharide units linked to hydroxylysine. Glomeruli from diabetics contain increased amounts of basement membrane material. In addition, these membranes show a distict chemical alteration c haracterized by a significant decrease in lysine, accoumpanied by an equivalent increase in hydroxylysine and hydroxylysine-linked disaccharide units.

Pancreatic carcinoma is characterized by elevated content of hyaluronan and chondroitin sulfate with altered disaccharide composition

The amount and the types of glycosaminoglycans (GAGs) present in human pancreatic carcinoma were examined and compared with those in normal pancreas. Human pancreatic carcinoma contained increased levels (4-fold) of total GAGs. Particularly, this carcinoma is characterized by a 12-fold increase of hyaluronan (HA) and a 22-fold increase in chondroitin sulfate (CS) content. CS in pancreatic carcinoma exhibited an altered disaccharide composition which is associated with marked increase of non-sulfated and 6-sulfated disaccharides. Dermatan sulfate (DS) was also increased (1.5-fold) in carcinoma, whereas heparan sulfate (HS), the major GAG of normal pancreas, becomes the minor GAG in pancreatic carcinoma without significant changes in the content and in molecular size. In all cases, the galactosaminoglycans (GalGAGs, i.e. CS and DS) derived from pancreatic carcinomas were of lower molecular size compared to those from normal pancreas. The results in this study indicate, for the first time, that human pancreatic carcinoma is characterized by highly increased amounts of HA and of a structurally altered CS.

Highly sulfated dermatan sulfates from Ascidians. Structure versus anticoagulant activity of these glycosaminoglycans

Dermatan sulfates with the same backbone structure [4-alpha-L-IdceA-1-->3-beta-D-GalNAc-1]n but with different patterns of sulfation substitutions have been isolated from the ascidian body. All the ascidian dermatan sulfates have a high content of 2-O-sulfated alpha-L-iduronic acid residues but differ in the pattern of sulfation of the N-acetyl-beta-D-galactosamine units. Styela plicata and Halocynthia pyriformis have 4-O-sulfated units, but in Ascidian nigra they are 6-O-sulfated. This collection of ascidian dermatan sulfates (together with native and oversulfated mammalian dermatan sulfate), where the extent and position of sulfate substitution have been fully characterized, were tested in anticoagulant assays. Dermatan sulfate from A. nigra has no discernible anticoagulant activity, which indicates that 4-O-sulfation of the N-acetyl-beta-D-galactosamine is essential for the anticoagulant activity of this glycosaminoglycan. In contrast dermatan sulfates from S. plicata and H. pyriformis are potent anticoagulants due to potentiation of thrombin inhibition by heparin cofactor II. These ascidian dermatan sulfates have approximately 10-fold and approximately 6-fold higher activity with heparin cofactor II than native and an oversulfated mammalian dermatan sulfate, respectively. They have no effect on thrombin or factor Xa inhibition by antithrombin. These naturally oversulfated ascidian dermatan sulfates are sulfated at selected sites required for interaction with heparin cofactor II and thus have specific and potent anticoagulant activity.

Fluorescent chemosensors for carbohydrates: a decade's worth of bright spies for saccharides in review

This review provides a chronological survey of over fifty fluorescent chemosensors for carbohydrates from the period between 1992 to the present. The survey contains only those sensors that are synthetic or chemosensory, utilize boronic acids and display a fluorescence response in the form of intensity changes or shifts in wavelength. With each compound listed, a description of the saccharide probe is given with regard to concentration, excitation and emission wavelengths, pH and solvent mixture proportions. In addition, the selectivity of each chemosensor is provided as well as the trends in binding constants. Where possible, a description of the fluorescence signaling mechanism is given as well as commentary on the probe's unique features within this class of sensors.

Thiols of intracellular pathogens. Identification of ovothiol A in Leishmania donovani and structural analysis of a novel thiol from Mycobacterium bovis

Leishmania donovani, the causative agent of visceral leishmaniases, is an intracellular pathogen which proliferates within the host macrophages. Analysis of the thiol composition of L. donovani by means of the thiol-specific reagent, 7-diethylamino-3-(4'-maleimidylphenyl)-4-methylcoumarin, indicated that this organism produces substantial amounts of ovothiol A. This observation was further substantiated by HPLC of extracts of L. donovani after derivatization with bromobimane. L. donovani extracts contained a thiol, the bimane derivative of which had identical retention time and fluorescence quenching to a thiol from Crithidia fasciculata, which had previously been identified as ovothiol A. By comparison, the intracellular bacterial pathogen, Mycobacterium bovis, contained only one major low-molecular-mass thiol, which was assigned the trivial name mycothiol. The structure of the bimane derivative of mycothiol was solved by a combination of one- and two-dimensional 1H and 13C NMR spectroscopy. Spatial relationships in the molecule were further refined by NOE experiments and allowed identification of mycothiol as 1-D-myo-inositol-2-(N-acetyl-L-cysteinyl)amino-2-deoxy-alpha-D-glucopyra noside. This assignment was confirmed by positive-ion fast-atom-bombardment mass spectrometry which gave m/z = 677.6 Da and a sodiated species at 699.6 Da. Analysis of the dansylated hydrolysis products of performic-acid-oxidized mycothiol indicated the presence of 0.85 mol glucosamine and 1.02 mol cysteic acid/mol sulfhydryl groups. Crude extracts of M. bovis contained an enzyme which catalysed the NAD(P)H2-dependent reduction of mycothiol disulfide to the free thiol. Analysis of perchloric acid extracts of Mycobacterium tuberculosis H37RV indicated the presence of a thiol which comigrated with mycothiol, both as the free thiol and as the 7-diethylamino-3-(4'-maleimidylphenyl)-4-methylcoumarin and bimane derivatives, on reverse-phase HPLC. The significance of these findings in terms of the evasion of the host defense mechanisms by leishmania parasites and mycobacteria is considered.