The cyanobacterial hepatotoxin microcystin binds to proteins and increases the fitness of microcystis under oxidative stress conditions
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...
Saved in:
Published in | PloS one Vol. 6; no. 3; p. e17615 |
---|---|
Main Authors | , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Public Library of Science
18.03.2011
Public Library of Science (PLoS) |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | 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 of the Calvin cycle, phycobiliproteins and two NADPH-dependent reductases. We have discovered that microcystin binds to a number of these proteins in vivo and that the binding is strongly enhanced under high light and oxidative stress conditions. The nature of this binding was studied using extracts of a microcystin-deficient mutant in vitro. The data obtained provided clear evidence for a covalent interaction of the toxin with cysteine residues of proteins. A detailed investigation of one of the binding partners, the large subunit of RubisCO showed a lower susceptibility to proteases in the presence of microcystin in the wild type. Finally, the mutant defective in microcystin production exhibited a clearly increased sensitivity under high light conditions and after hydrogen peroxide treatment. Taken together, our data suggest a protein-modulating role for microcystin within the producing cell, which represents a new addition to the catalogue of functions that have been discussed for microbial secondary metabolites. |
---|---|
Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 Conceived and designed the experiments: ED MH AK TB. Performed the experiments: YZ J-CK S. Meissner. Analyzed the data: YZ S. Mikkat. Contributed reagents/materials/analysis tools: KI. Wrote the paper: ED. |
ISSN: | 1932-6203 1932-6203 |
DOI: | 10.1371/journal.pone.0017615 |