Dataset Information

Isolation and Characterization of [DLeu1]microcystin-LY from Microcystis aeruginosa CPCC-464.

ABSTRACT: [D-Leu1]MC-LY (1) ([M + H]+ m/z 1044.5673, ? 2.0 ppm), a new microcystin, was isolated from Microcystis aeruginosa strain CPCC464. The compound was characterized by 1H and 13C NMR spectroscopy, liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS) and UV spectroscopy. A calibration reference material was produced after quantitation by 1H NMR spectroscopy and LC with chemiluminescence nitrogen detection. The potency of 1 in a protein phosphatase 2A inhibition assay was essentially the same as for MCLR (2). Related microcystins, [D-Leu1]MC-LR (3) ([M + H]+ m/z 1037.6041, ? 1.0 ppm), [D-Leu1]MC-M(O)R (6) ([M + H]+ m/z 1071.5565, ? 2.0 ppm) and [D-Leu1]MC-MR (7) ([M + H]+ m/z 1055.5617, ? 2.2 ppm), were also identified in culture extracts, along with traces of [D-Leu1]MC-M(O2)R (8) ([M + H]+ m/z 1087.5510, ? 1.6 ppm), by a combination of chemical derivatization and LC-HRMS/MS experiments. The relative abundances of 1, 3, 6, 7 and 8 in a freshly extracted culture in the positive ionization mode LC-HRMS were ca. 84, 100, 3.0, 11 and 0.05, respectively. These and other results indicate that [D-Leu1]-containing MCs may be more common in cyanobacterial blooms than is generally appreciated but are easily overlooked with standard targeted LC-MS/MS screening methods.

SUBMITTER: LeBlanc P

PROVIDER: S-EPMC7076857 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Isolation and Characterization of [DLeu1]microcystin-LY from Microcystis aeruginosa CPCC-464.

LeBlanc Patricia P Merkley Nadine N Thomas Krista K Lewis Nancy I NI Békri Khalida K Renaud Susan LeBlanc SL Pick Frances R FR McCarron Pearse P Miles Christopher O CO Quilliam Michael A MA

Toxins 20200123 2

[D-Leu1]MC-LY (1) ([M + H]+m/z 1044.5673, Δ 2.0 ppm), a new microcystin, was isolated from Microcystis aeruginosa strain CPCC464. The compound was characterized by 1H and 13C NMR spectroscopy, liquid chromatography-high resolution tandem mass spectrometry (LC-HRMS/MS) and UV spectroscopy. A calibration reference material was produced after quantitation by 1H NMR spectroscopy and LC with chemiluminescence nitrogen ...[more]

PMID: 31979406

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Project description:The adverse effects of microcystin (MC) produced by cyanobacteria have drawn considerable attention from the public. Yet it remains unclear whether MC confers any benefits to the cyanobacteria themselves. One suggested function of MC is complexation, which may influence the bioaccumulation and toxicity of trace metals. To test this hypothesis, we examined Cd toxicity to wild-type Microcystis aeruginosa PCC 7806 (WT) and its MC-lacking mutant (MT) under nutrient-enriched (+NP), phosphorus-limited (-P), and nitrogen-limited (-N) conditions. The accumulation of Cd and the biochemical parameters associated with its detoxification [total phosphorus (TP), inorganic polyphosphate (Poly-P), and glutathione (GSH) in the cells as well as intra- and extra-cellular carbohydrates] were quantified. Although the -P cyanobacteria accumulated less Cd than their +NP and -N counterparts, the different nutrient-conditioned cyanobacteria were similarly inhibited by similar free ion concentration of Cd in the medium ([Cd2+]F). Such good toxicity predictability of [Cd2+]F was ascribed to the synchronous decrease in the intracellular concentrations of Cd and TP. Nevertheless, Cd toxicity was still determined by the intracellular Cd to phosphorus ratio (Cd/P), in accordance with what has been reported in the literature. On the other hand, the concentrations of TP, Poly-P, and carbohydrates went up, but GSH concentration dropped down with the enhancement of [Cd2+]F, indicating their association with Cd detoxification. Although the inactivation of MC peptide synthetase gene had some nutrient and Cd concentration dependent effects on the parameters above, both cyanobacterial strains showed the same Cd accumulation ability and displayed similar Cd sensitivity. These results suggest that MC cannot affect metal toxicity either by regulating metal accumulation or by altering the detoxification ability of the cyanobacteria. Other possible functions of MC need to be further investigated.

Dataset Information

Isolation and Characterization of [DLeu1]microcystin-LY from Microcystis aeruginosa CPCC-464.

Publications

Isolation and Characterization of [DLeu<sup>1</sup>]microcystin-LY from <i>Microcystis aeruginosa</i> CPCC-464.

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