Cyanopeptolins (CPs) are a class of

oligopeptide An oligopeptide ('' oligo-'', "a few"), is a peptide consisting of two to twenty amino acids, including dipeptides, tripeptides, tetrapeptides, and other polypeptides. Some of the major classes of naturally occurring oligopeptides include aerugi ...

s produced by

Microcystis ''Microcystis'' is a genus of freshwater cyanobacteria that includes the harmful algal bloom-forming '' Microcystis aeruginosa''. Over the last few decades, cyanobacterial blooms caused by eutrophication have become a major environmental proble ...

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 heterocyst, heterocysts and no akinetes. ''Plankto ...

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 – specifical ...

. The production of cyanopeptolins occurs through

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

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. They are derived from the corresponding hydroxycarboxylic acids by esterification. They can be saturated or unsaturated. Lactones are formed by lactonization, the intramolecular esterification of the corresp ...

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 when dissolved in water), 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 () (sometimes called molecular weight or formula weight, but see related quantities for usage) of a chemical substance ( element or compound) is defined as the ratio between the mass () and the amount of substance ...

. 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 Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

and

eutrophication Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

of inland waters promote blooms of

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

, 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. Serin ...

inhibitor Inhibitor or inhibition may refer to: Biology * Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity * Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotransmi ...

s. Cyanopeptolin CP1020 exposure in

zebrafish The zebrafish (''Danio rerio'') is a species of freshwater ray-finned fish belonging to the family Danionidae of the order Cypriniformes. Native to South Asia, it is a popular aquarium fish, frequently sold under the trade name zebra danio (an ...

affected pathways related to DNA damage, the

circadian rhythm A circadian rhythm (), or circadian cycle, is a natural oscillation that repeats roughly every 24 hours. Circadian rhythms can refer to any process that originates within an organism (i.e., Endogeny (biology), endogenous) and responds to the env ...

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 horizontally.

References

External links