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Microcystin, a hepatotoxin known to be the cause of animal and human deaths, is produced by the bloom-forming cyanobacterium Microcystis aeruginosa in freshwater bodies worldwide. The toxin is produced nonribosomally via a multifunctional enzyme complex, consisting of both peptide synthetase and polyketide synthase modules coded for by the mcy gene cluster.(More)
The effects of microcystins on Daphnia galeata, a typical filter-feeding grazer in eutrophic lakes, were investigated. To do this, the microcystin-producing wild-type strain Microcystis aeruginosa PCC7806 was compared with a mcy- PCC7806 mutant, which could not synthesize any variant of microcystin due to mutation of a microcystin synthetase gene. The(More)
We investigated the intestinal uptake and adverse effects of microcystins ingested with Microcystis on Daphnia galeata. The gut structure, blood microcystin concentration, appearance, and movements of Daphnia fed Microcystis PCC 7806 or a microcystin-deficient PCC 7806 mutant were monitored over time. Microcystins were rapidly taken up from the digestive(More)
Microcystins represent an extraordinarily large family of cyclic heptapeptide toxins that are nonribosomally synthesized by various cyanobacteria. Microcystins specifically inhibit the eukaryotic protein phosphatases 1 and 2A. Their outstanding variability makes them particularly useful for studies on the evolution of structure-function relationships in(More)
BACKGROUND The colonial cyanobacterium Microcystis proliferates in a wide range of freshwater ecosystems and is exposed to changing environmental factors during its life cycle. Microcystis blooms are often toxic, potentially fatal to animals and humans, and may cause environmental problems. There has been little investigation of the genomics of these(More)
This review presents recommended nomenclature for the biosynthesis of ribosomally synthesized and post-translationally modified peptides (RiPPs), a rapidly growing class of natural products. The current knowledge regarding the biosynthesis of the >20 distinct compound classes is also reviewed, and commonalities are discussed.
Nonribosomal peptide synthesis is achieved in prokaryotes and lower eukaryotes by the thiotemplate function of large, modular enzyme complexes known collectively as peptide synthetases. These and other multifunctional enzyme complexes, such as polyketide synthases, are of interest due to their use in unnatural-product or combinatorial biosynthesis (R.(More)
Microcystins are cyanobacterial toxins that represent a serious threat to drinking water and recreational lakes worldwide. Here, we show that microcystin fulfils an important function within cells of its natural producer Microcystis. The microcystin deficient mutant ΔmcyB showed significant changes in the accumulation of proteins, including several enzymes(More)
Microcystis is a well-known cyanobacterial genus frequently producing hepatotoxins named microcystins. Toxin production is encoded by microcystin genes (mcy). This study aims (i) to relate the mcy occurrence in individual colonies to the presence of microcystin, (ii) to assess whether morphological characteristics (morphospecies) are related to the(More)
Microcystin is a potent inhibitor of eukaryotic protein phosphatases and has been implicated in causing hepatotoxicity to humans and animals worldwide. It is produced primarily by the bloom-forming cyanobacterium Microcystis aeruginosa, although the function of the peptide in this micro-organism is unknown. In this study, a microcystin-related protein,(More)