title: Functional assessment of mycosporine-like amino acids in Microcystis aeruginosa strain PCC 7806.
abstract: The biological role of the widespread mycosporine-like amino acids (MAAs) in cyanobacteria is under debate. Here, we have constructed and characterized two mutants impaired in MAA biosynthesis in the bloom-forming cyanobacterium Microcystis aeruginosa PCC 7806. We could identify shinorine as the sole MAA type of the strain, which is exclusively located in the extracellular matrix. Bioinformatic studies as wells as polymerase chain reaction screening revealed that the ability to produce MAAs is sporadically distributed within the genus. Growth experiments and reactive oxygen species quantification with wild-type and mutant strains did not support a role of shinorine in protection against UV or other stress conditions in M. aeruginosa PCC 7806. The shinorine content per dry weight of cells as well as transcription of the mys gene cluster was not significantly elevated in response to UV-A, UV-B or any other stress condition tested. Remarkably, both mutants exhibited pronounced morphological changes compared with the wild type. We observed an increased accumulation and an enhanced hydrophobicity of the extracellular matrix. Our study suggests that MAAs in Microcystis play a negligible role in protection against UV radiation but might be a strain-specific trait involved in extracellular matrix formation and cell-cell interaction.
authors: Department of Microbiology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24/25, Potsdam-Golm, 14476, Germany.
authors: Chenlin
authors: C
authors: Hu
authors: Ginka
authors: G
authors: Völler
authors: Roderich
authors: R
authors: Süßmuth
authors: Elke
authors: E
authors: Dittmann
authors: Jan-Christoph
authors: JC
authors: Kehr
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D003514:Cyclohexylamines / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D005998:Glycine / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism; D046931:Microcystis / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family; D009154:Mutation / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000596:Amino Acids; D003514:Cyclohexylamines; D017382:Reactive Oxygen Species; C494891:shinorine; D005998:Glycine