New types of ATP-grasp ligase are associated with the novel pathway for complicated mycosporine-like amino acid production in desiccation-tolerant cyanobacteria.

Mycosporine-like amino acids (MAAs) were widespread in diverse organisms to attenuate UV radiation. We recently characterized the large, complicated MAA mycosporine-2-(4-deoxygadusolyl-ornithine) in desert cyanobacterium Nostoc flagelliforme. Synthesis of this MAA requires the five-gene cluster mysABDC2C3. Here, bioinformatic analysis indicated that mysC duplication within five-gene mys clusters is strictly limited to drought-tolerant cyanobacteria. Phylogenic analysis distinguished these duplicated MysCs into two clades that separated from canonical MysCs. Heterologous expression of N. flagelliforme mys genes in Escherichia coli showed that MysAB produces 4-deoxygadusol. The ATP-grasp ligase of MysC3 catalyses the linkage of the δ- or ε-amino group of ornithine/lysine to 4-deoxygadusol, yielding mycosporine-ornithine or mycosporine-lysine respectively. The ATP-grasp ligase of MysC2 strictly condenses the α-amino group of mycosporine-ornithine to another 4-deoxygadusol. MysD (D-Ala-D-Ala ligase) functions following MysC2 to catalyse the formation of mycosporine-2-(4-deoxygadusolyl-ornithine). High arginine content likely provides a greater pool of ornithine over other amino acids during rehydration of desiccated N. flagelliforme. Duplication of ATP-grasp ligases is specific for the use of substrates that have two amino groups (such as ornithine) for the production of complicated MAAs with multiple chromophores. This five-enzyme biosynthesis pathway for complicated MAAs is a novel adaptation of cyanobacteria for UV tolerance in drought environments.

UV-B induced biosynthesis of a novel sunscreen compound in solar radiation and desiccation tolerant cyanobacteria.

The small-molecule sunscreen compounds, mycosporine-like amino acids (MAAs), have strong ultraviolet (UV) absorption and can protect cyanobacteria against UV-B damage. However, the molecular mechanism underlying UV-B signaling and MAA chemical diversity remain largely unclear. Here, we identified a five-gene cluster for MAA biosynthesis in the solar radiation and desiccation tolerant cyanobacterium Nostoc flagelliforme. A LuxR family protein OrrA was identified as a positive UV-B responsive regulator binding to the promoter region of this gene cluster. OrrA functions as an activator mediating the UV-B induced MAA biosynthesis. Overexpression of orrA strengthened its UV-B tolerance during desiccation, and enhanced the photosynthetic recovery upon rehydration. Heterologous expression of this gene cluster in Anabaena PCC 7120 produces the same MAA as that in field samples of N. flagelliforme. The MAA structure is assigned as mycosporine-2-(4-deoxygadusolyl-ornithine) with a molecular weight of 756 Da, the structurally unique MAA compound reported to date. This MAA was catalyzed by mysD-mysC2-mysC1 encoding proteins from 4-deoxygadusol, which was synthesized through the catalysis of mysA-mysB products. Thus, we elucidated the transcriptional mechanism for a novel type MAA biosynthesis in solar radiation and desiccation tolerant cyanobacteria, which shed light on the identification of other components for UV-B signaling in cyanobacteria.

Identification, Characteristics and Mechanism of 1-Deoxy-N-acetylglucosamine from Deep-Sea Virgibacillus dokdonensis MCCC 1A00493.

Xanthomonas oryzae pv. oryzae, which causes rice bacterial blight, is one of the most destructive pathogenic bacteria. Biological control against plant pathogens has recently received increasing interest. 1-Deoxy-N-acetylglucosamine (1-DGlcNAc) was extracted from the supernatant of Virgibacillus dokdonensis MCCC 1A00493 fermentation through antibacterial bioassay-guided isolation. Its structure was elucidated by LC/MS, NMR, chemical synthesis and time-dependent density functional theory (TD-DFT) calculations. 1-DGlcNAc specifically suppressed X. oryzae pv. oryzae PXO99A (MIC was 23.90 µg/mL), but not other common pathogens including Xanthomonas campestris pv. campestris str.8004 and Xanthomonas oryzae pv. oryzicola RS105. However, its diastereomer (2-acetamido-1,5-anhydro-2-deoxy-d-mannitol) also has no activity to X. oryzae pv. oryzae. This result suggested that activity of 1-DGlcNAc was related to the difference in the spatial conformation of the 2-acetamido moiety, which might be attributed to their different interactions with a receptor. Eighty-four unique proteins were found in X. oryzae pv. oryzae PXO99A compared with the genome of strains8004 and RS105 by blastp. There may be unique interactions between 1-DGlcNAc and one or more of these unique proteins in X. oryzae pv. oryzae. Quantitative real-time PCR and the pharmMapper server indicated that proteins involved in cell division could be the targets in PXO99A. This research suggested that specificity of active substance was based on the active group and spatial conformation selection, and these unique proteins could help to reveal the specific mechanism of action of 1-DGlcNAc against PXO99A.

Correlative analysis of neoplasm patients with phlegm-stasis or abnormal Savda syndrome, based on metabonomics.

OBJECTIVE: To investigate plasma samples from neoplasm patients with phlegm-stasis or abnormal Savda syndrome, with NMR spectroscopy, and to analyze their metabolic varieties, characteristics and reciprocity. METHODS: 1H-NMR spectra were analyzed using the orthogonal projection to latent structure with discriminative analysis (OPLS-DA) method with unit variance scaling. The discriminative significance of metabolites was determined by the Pearson's product - moment correlation coefficient. RESULTS: Compared to the control group, neoplasm patients with phlegm - stasis or abnormal Savda syndrome had low concentrations of leucine, isoleucine, valine, alanine, tyrosine, histidine, citrulline, glycoprotein, glutamine, myo-inositol, scyllo-inositol, creatine, alpha-glucose, alpha-glucose and lactate (P < 0.05), and high concentrations of very low density lipoprotein, low density lipoprotein, unsaturated lipid, formate, acetone, acetate, acetoacetate, pyruvate, beta-hydroxybutyrate, carnitine and malonic acid (P < 0.05), with no significant differences between the phlegm - stasis and abnormal Savda syndrome patients. CONCLUSIONS: Neoplasm patients with different syndromes have very similar metabolic changes. A series of abnormalities such as immune dysfunction and oxidative - antioxidative imbalance, occur in neoplasm patients with abnormal Savda or phlegm - stasis syndrome.

Plasma metabonomic analysis with ¹H nuclear magnetic resonance revealing the relationship of different tumors and the disease homology theory of traditional Uyghur medicine.

OBJECTIVE: To investigate the plasma samples obtained from tumor patients using (1)H nuclear magnetic resonance (NMR) spectroscopy, and find the biochemical foundation of abnormal Savda described in traditional Uyghur medicine. METHODS: A total of 170 tumor patients with abnormal Savda syndrome who were confirmed clinically were enrolled in this study, and 50 healthy volunteers were set up as controls. The plasma (1)H NMR spectra were analyzed using the orthogonal projection to latent structure with discriminant analysis (OPLS-DA) method with unit variance scaling. The discriminative significance of the metabolites was determined using the Pearson's product-moment correlation coefficient. RESULTS: Compared with the healthy controls, the tumor patients with abnormal Savda syndrome had uniformly correlative low levels of leucine, isoleucine, valine, histidine, tyrosine, alanine, glutamine, creatine, inositol, α-glucose, and ß-glucose (P<0.05), but had significantly high levels of formate, malonic acid, acetone, acetate, acetoacetate, pyruvate, ß-hydroxy butyrate, carnitine and lipidtemns such as very low density lipoprotein, low density lipoprotein and unsaturated lipids (P<0.05). CONCLUSION: Tumor patients with abnormal Savda syndrome had similar metabolic changes and characteristics, which indicated a similar pathogenetic process and provides some biochemical basis for traditional Uyghur medicine theory.