Structural determination of the sheath-forming polysaccharide of Sphaerotilus montanus using thiopeptidoglycan lyase which recognizes the 1,4 linkage between α-d-GalN and β-d-GlcA

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2021-2022

The use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the analysis of carbohydrates and glycoconjugates is a well-established technique and this review is the 12th update of the original article published in 1999 and brings coverage of the literature to the end of 2022. As with previous review, this review also includes a few papers that describe methods appropriate to analysis by MALDI, such as sample preparation, even though the ionization method is not MALDI. The review follows the same format as previous reviews. It is divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of computer software for structural identification. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other general areas such as medicine, industrial processes, natural products and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. MALDI is still an ideal technique for carbohydrate analysis, particularly in its ability to produce single ions from each analyte and advancements in the technique and range of applications show little sign of diminishing.

Taxonomic characterization of Sphaerotilus microaerophilus sp. nov., a sheath-forming microaerophilic bacterium of activated sludge origin

A microaerophilic Gram-stain-negative bacilliform bacterial strain, FB-5 T, was isolated from activated sludge in Yokohama, Japan, that exhibited filamentous growth and formed a microtube (sheath). Cells were motile using a single polar flagellum. The optimum growth temperature and pH were 30 °C and 7.5, respectively. Strain FB-5 T was catalase-negative. Peptides and amino acids were utilized as energy and carbon sources. Sugars and organic acids were not utilized. Vitamin B12 enhanced the growth of strain FB-5 T. Sulfur-dependent lithotrophic growth was possible. Major respiratory quinone was UQ-8. Major fatty acids were C16:1ω7 and C16:0. The genomic DNA G + C content was 69.16%. Phylogenetic analysis of the 16S rRNA gene suggested that strain FB-5 T belongs to the genus Sphaerotilus. The close relatives were S. natans subsup. sulfidivorans and S. natans subsup. natans with 98.0% and 97.8% similarity based on the 16S rRNA gene analysis, respectively. The genome size (6.06 Mbp) was larger than that (4.39-5.07 Mbp) of the Sphaerotilus strains. The AAI values against the related strains ranged from 71.0 to 72.5%. The range of ANI values was 81.7 - 82.5%. In addition to these distinguishable features of the genome, the core genome and dDDH analyses suggested that this strain is a novel member of the genus Sphaerotilus. Based on its physiological properties and genomic features, strain FB-5 T is considered as a novel species of the genus Sphaerotilus, for which the name S. microaerophilus sp. nov. is proposed. The type strain is FB-5 T (= JCM 35424 T = KACC 23146 T).

Modified acid polysaccharide derived from Salvia przewalskii with excellent wound healing and enhanced bioactivity

Acid polysaccharide was extracted from Salvia przewalskii root powders (PSP), purified by diethylaminoethyl cellulose column (DEAE-52) and molecular sieve (PSP2). PSPm1 was obtained by modifying PSP2 with nitrite and phosphoric acid. The chemical structure of PSP2 and PSPm1 exhibited notable distinctions, primarily due to the absence of arabinose and promotion of glucuronic acid (GlcA). The structure of PSPm1 was deduced through the utilization of 1H, 13C, and 2-D NMR. The main chain was linked by α-D-Galp(1 → 3)-α-Glcp-(1 → fragments and →6)-β-D-Galp fragments, with the presence of →4)-α-D-GlcpA-(1 → 6)-β-D-Galp-(1 → ， → 4)-α-D-GalAp-(1 → 2,4)-α-D-Rhap-(1 → fragments and →6)-α-Glcp-(1 → 2,4)-β-D-Manp-(1 → fragments. PSPm1 exhibited different immunoregulatory bioactivity in vitro, including haemostatic effects indicated by activated clotting time of 55.5 % reduction by the activated clotting time (ACT) test and wound healing function in vivo. PSPm1 also displayed better anti-tumor biological effects than unmodified. The structure-activity dissimilarity between PSP2 and PSPm1 primarily stems from variations in molecular weight (Mw), monosaccharide composition, and branching patterns. The modification of polysaccharides from the extract residues of Chinese medicinal materials may be a new form of drug supplements.

Enzymatic degradation of glucosaminoglucan and cellulase resistance of cellulose nanofiber coated with glucosaminoglucan

AIMS

Enzymatic degradation of β-1,4-linked glucose and glucosamine (glucosaminoglucan, GG), which is prepared from Thiothrix nivea and can act as a cellulose-aminating agent with a strong affinity to cellulose, was attempted.

METHODS AND RESULTS

A chitosanase-secreting fungal strain was isolated as a GG-degrading microbe. GG was found to be degraded by not only chitosanases but also cellulases. Based on nuclear magnetic resonance spectroscopy, both enzymes were found to produce GlcN-Glc from GG. The cellulases also produced GlcN-Glc-GlcN-Glc as an additional final digest. Furthermore, aminated (GG-coated) cellulose nanofibers exhibited cellulase resistance. The flexibility of GG adsorbed onto a cellulose crystal was almost identical to that of cellulose, as estimated via the molecular dynamics calculations.

CONCLUSIONS

The chitosanase and cellulase hydrolyzed the β-1,4-linkage from Glc to GlcN and were expected to recognize the tetramer and hexamer units of GG depending on their final products. The cellulose nanofibers acquired cellulase resistance via amination with GG, probably because of the lower activity of cellulase to GG than cellulose.

A heterodimeric hyaluronate lyase secreted by the activated sludge bacterium Haliscomenobacter hydrossis

Haliscomenobacter hydrossis is a filamentous bacterium common in activated sludge. The bacterium was found to utilize hyaluronic acid, and hyaluronate lyase activity was detected in its culture. However, no hyaluronate lyase gene was found in the genome, suggesting the bacterium secretes a novel hyaluronate lyase. The purified enzyme exhibited two bands on SDS-PAGE and a single peak on gel filtration chromatography, suggesting a heterodimeric composition. N-terminal amino acid sequence and mass spectrometric analyses suggested that the subunits are molybdopterin-binding and [2Fe-2S]-binding subunits of a xanthine oxidase family protein. The presence of the cofactors was confirmed using spectrometric analysis. Oxidase activity was not detected, revealing that the enzyme is not an oxidase but a hyaluronate lyase. Nuclear magnetic resonance analysis of the enzymatic digest revealed that the enzyme breaks hyaluronic acid to 3-(4-deoxy-β-d-gluc-4-enuronosyl)-N-acetyl-d-glucosamine. As hyaluronate lyases (EC 4.2.2.1) are monomeric or trimeric, the enzyme is the first heterodimeric hyaluronate lyase.

Maresin 1 protects against lipopolysaccharide/d-galactosamine-induced acute liver injury by inhibiting macrophage pyroptosis and inflammatory response

BACKGROUND

Acute liver injury (ALI) caused by sepsis is a fearful disease with high mortality and poor prognosis. This study aimed to explore the roles and mechanism of Maresin 1 (MaR1) in lipopolysaccharide/d-galactosamine (LPS/D-GalN)-induced ALI.

METHODS

We established an ALI mouse model induced by LPS/D-GalN. Each group was treated with or without LPS/D-GalN or MaR1. For the vitro experiments, RAW264.7, NCTC1469 cells, and bone marrow-derived macrophages (BMDMs) were stimulated with LPS. The effects of MaR1 on the reactive oxygen species (ROS), pyroptosis and inflammatory response in macrophages were investigated.

RESULTS

MaR1 significantly inhibited an excessive inflammatory response and proinflammatory markers during LPS/D-GalN-induced ALI. MaR1 markedly decreased the levels of ROS, tumor necrosis factor-α, and interleukin-1β (IL-1β) in macrophages, and limited hepatocyte apoptosis in vitro. Upon exploring the mechanisms underlying the protective role of MaR1, we found MaR1 markedly upregulated the nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and considerably reduced the phosphorylation of p38, ERK, and nuclear factor-kappa B (NF-κB)-p65. Knocking down Nrf2 decreased the effect of MaR1. Furthermore, we observed that MaR1 reduced inflammatory injury by inhibiting M1 macrophages and promoting M2 macrophage polarization. Finally, we observed that MaR1 could inhibit the production of gasdermin D N-terminus (GSDMD-N) in vivo. In vitro, MaR1 could significantly suppressed the expression of NLR family pyrin domain containing 3 (NLRP3) inflammasome, GSDMD-N, and IL-1β caused by LPS and nigericin stimulation in BMDMs.

CONCLUSION

MaR1 could ameliorate inflammation during LPS/D-GalN induced ALI by suppressing mitogen-activated protein kinase /NF-κB signaling and NLRP3 inflammasome-induced pyroptosis, activating macrophage M1/M2 polarization and Nrf2/HO-1 signaling. This provides new evidence for the potential of developing MaR1 for ALI treatment.