Abstract Title
Non-canonical carbon fixation in microcystin-producing cyanobacteria
Start Date
24-5-2022 4:00 PM
End Date
24-5-2022 4:15 PM
Abstract
Arthur Guljamow1, Tino Barchewitz1, Stefan Timm2, Martin Hagemann2, Elke Dittmann1
1Department of Microbiology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Street 24/25, 14476 Potsdam-Golm, Germany
2Department of Plant Physiology, Institute of Biological Sciences, University of Rostock, Albert-Einstein-Street 3, 18059 Rostock, Germany
The success of the bloom-forming genus Microcystis is closely linked to its ability to produce a number of signature metabolites including the potent hepatotoxin microcystin. Recent studies on the role of microcystin have pointed to a role of the heptapeptide in inorganic carbon adaptation of Microcystis. In particular, microcystin binds to proteins of the Calvin-Benson cycle including the key enzyme RubisCO. Subsequent studies on the subcellular localization of RubisCO in the model strain M. aeruginosa PCC 7806 and its DmcyB mutant revealed not only pronounced differences between the genotypes but also a frequent non-canonical localization of RubisCO underneath the cytoplasmic membrane. To further dissect the peculiarities of Microcystis RubisCO and the role of microcystin, we have heterologously expressed the enzyme in the cyanobacterial model strain Synechocystis sp. PCC 6803. We could thereby address both in vivo and in vitro differences of the RubisCO variants and the influence of microcystin separately. Comprehensive data from enzyme assays, crystal structure analysis, immunofluorescent microscopic analyses and native mass spectrometry indicate significant differences between Microcystis and Synechocystis in the efficiency, dynamics, and orchestration of carbon fixation. We hypothesize that microcystin contributes significantly to the plasticity of carbon fixation and to the versatility of bloom-forming cyanobacteria.
Non-canonical carbon fixation in microcystin-producing cyanobacteria
Arthur Guljamow1, Tino Barchewitz1, Stefan Timm2, Martin Hagemann2, Elke Dittmann1
1Department of Microbiology, Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Street 24/25, 14476 Potsdam-Golm, Germany
2Department of Plant Physiology, Institute of Biological Sciences, University of Rostock, Albert-Einstein-Street 3, 18059 Rostock, Germany
The success of the bloom-forming genus Microcystis is closely linked to its ability to produce a number of signature metabolites including the potent hepatotoxin microcystin. Recent studies on the role of microcystin have pointed to a role of the heptapeptide in inorganic carbon adaptation of Microcystis. In particular, microcystin binds to proteins of the Calvin-Benson cycle including the key enzyme RubisCO. Subsequent studies on the subcellular localization of RubisCO in the model strain M. aeruginosa PCC 7806 and its DmcyB mutant revealed not only pronounced differences between the genotypes but also a frequent non-canonical localization of RubisCO underneath the cytoplasmic membrane. To further dissect the peculiarities of Microcystis RubisCO and the role of microcystin, we have heterologously expressed the enzyme in the cyanobacterial model strain Synechocystis sp. PCC 6803. We could thereby address both in vivo and in vitro differences of the RubisCO variants and the influence of microcystin separately. Comprehensive data from enzyme assays, crystal structure analysis, immunofluorescent microscopic analyses and native mass spectrometry indicate significant differences between Microcystis and Synechocystis in the efficiency, dynamics, and orchestration of carbon fixation. We hypothesize that microcystin contributes significantly to the plasticity of carbon fixation and to the versatility of bloom-forming cyanobacteria.