Cyanopeptolins (CPs) are a class of

oligopeptide An oligopeptide, often just called peptide ('' oligo-'', "a few"), consists of two to twenty amino acids and can include dipeptides, tripeptides, tetrapeptides, and pentapeptides. Some of the major classes of naturally occurring oligopeptides incl ...

s produced by

Microcystis ''Microcystis'' is a genus of freshwater cyanobacteria that includes the harmful algal bloom-forming ''Microcystis aeruginosa''. Many members of a ''Microcystis'' community can produce neurotoxins and hepatotoxins, such as microcystin and cyanop ...

and

Planktothrix ''Planktothrix'' is a diverse genus of filamentous cyanobacteria observed to amass in algal blooms in water ecosystems across the globe. Like all Oscillatoriales, ''Planktothrix'' species have no heterocysts and no akinetes. Planktothrix are uniq ...

algae strains, and can be

neurotoxic Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...

. The production of cyanopeptolins occurs through

nonribosomal peptide Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be made by bacter ...

s synthases (NRPS).

Chemistry

CPs are, in general, a six-residue peptide formed into a ring by a beta-

lactone Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. Lactones are formed by intramolecular esterification of the co ...

bridge, making them chemically depsipeptides (peptidolactones). The first position is usually

threonine Threonine (symbol Thr or T) is an amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH form under biological conditions), a carboxyl group (which is in the deprotonated −COO� ...

, which links to one or two residues via an ester bound on the beta-hydroxyl group; the third position is conserved to be 3-amino-6-hydroxy-2-piperidone (Ahp) or a derivative. All other positions are highly variable. There is not a single, unified nomenclature, for CPs. Names such as CP1020 and CP1138 refer to the

molar mass In chemistry, the molar mass of a chemical compound is defined as the mass of a sample of that compound divided by the amount of substance which is the number of moles in that sample, measured in moles. The molar mass is a bulk, not molecular, p ...

. Others, such as aeruginopeptins, micropeptins, microcystilide, nostopeptins, and oscillapeptins, refer to the organism the substance is originally found in.

Factors affecting production

Increased water temperatures, because of

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

and

eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytopla ...

of inland waters promote blooms of

cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...

, potentially threaten water contamination by the production of the toxic cyanopeptolin CP1020.

Biological activity

Most CPs are

serine protease Serine proteases (or serine endopeptidases) are enzymes that cleave peptide bonds in proteins. Serine serves as the nucleophilic amino acid at the (enzyme's) active site. They are found ubiquitously in both eukaryotes and prokaryotes. ...

inhibitors. Cyanopeptolin CP1020 exposure in

zebrafish The zebrafish (''Danio rerio'') is a freshwater fish belonging to the minnow family ( Cyprinidae) of the order Cypriniformes. Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio (and thus often ...

affected pathways related to DNA damage, the

circadian rhythm A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., Endogeny (biology), endogeno ...

and response to light.

Evolutionary history

CPs are probably very ancient: the cyanobacterial genera that produce CPs appear to have inherited the key modules vertically and not horizonatlly.

References

External links