Microcystin
Encyclopedia
Nonribosomal peptide
Nonribosomal peptides 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 bacteria inside these organisms...
s produced by cyanobacteria (e.g.Microcystis aeruginosa
Microcystis aeruginosa
Microcystis aeruginosa is a species of freshwater cyanobacteria which can form harmful algal blooms that are of economic and ecological importance...
). They are cyanotoxin
Cyanotoxin
Cyanotoxins are toxins produced by bacteria called cyanobacteria . Cyanobacteria are found almost everywhere, but particularly in lakes and in the ocean where, under certain conditions, they reproduce exponentially to form blooms. Blooming cyanobacteria can produce cyanotoxins in such...
s and can be very toxic for plants and animals including humans. Their hepatotoxicity may cause serious damage to the liver
Liver
The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...
. Microcystins can strongly inhibit protein phosphatases type 1 (PP1) and 2A (PP2A), and are linked to pansteatitis
Pansteatitis
Pansteatitis or Yellow fat disease, is a physiological condition in which the body fat becomes inflamed.-Causes:It is thought to be brought about by any or a combination of a number of factors which include...
.
Microcystins consist of several uncommon non-proteinogenic amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s such as dehydroalanine
Dehydroalanine
Dehydroalanine is an uncommon amino acid found in peptides of microbial origin ....
derivatives and the special β-amino acid ADDA
Adda
Adda can refer to:*Adda in Italy.*River Adda in Wales.*Adda , a concept/slang in South Asia, especial Bengal, also Addabazi.*Adda , an archaeological site in Nigeria.*Adda Corporation, a Taiwanese fan manufacturer....
((all-S,all-E)-3-Amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-diene acid).
Microcystin-LR is one of over 80 known toxic variants and is the most studied by chemists, pharmacologists, biologists and ecologists. Microcystin-containing 'blooms' are a problem worldwide, including China, Brazil, Australia, the United States and much of Europe. Once ingested, microcystin travels to the liver, via the bile acid transport system, where most is stored; though some remains in the blood stream and may contaminate tissue. Microcystin binds covalently to protein phosphatases thus disrupting cellular control processes.
There appears to be inadequate information to assess carcinogenic potential of microcystins by applying EPA Guidelines for Carcinogen Risk Assessment. A few studies suggest that there may be a relationship between liver and colorectral cancers and the occurrence of cyanobacteria in drinking water in China (Yu et al., 1989; Zhou et al., 2002). Evidence is, however, limited due to limited ability to accurately assess and measure exposure.
See also
- CyanotoxinCyanotoxinCyanotoxins are toxins produced by bacteria called cyanobacteria . Cyanobacteria are found almost everywhere, but particularly in lakes and in the ocean where, under certain conditions, they reproduce exponentially to form blooms. Blooming cyanobacteria can produce cyanotoxins in such...
- Harmful algal bloom
- LipopolysaccharideLipopolysaccharideLipopolysaccharides , also known as lipoglycans, are large molecules consisting of a lipid and a polysaccharide joined by a covalent bond; they are found in the outer membrane of Gram-negative bacteria, act as endotoxins and elicit strong immune responses in animals.-Functions:LPS is the major...
- NodularinNodularinNodularin-R is a cyclic nonribosomal peptide produced by the planktonic cyanobacterium Nodularia spumigena. This cyanobacterium forms blooms in brackish water bodies throughout the world. The late summer blooms of Nodularia spumigena are among the largest cyanobacterial mass occurrences in the world...
s - Nonribosomal peptideNonribosomal peptideNonribosomal peptides 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 bacteria inside these organisms...
s