Transcriptomics-aided dissection of the intracellular and extracellular roles of microcystin in Microcystis aeruginosa PCC 7806.
Recent studies have provided evidence for both intracellular and extracellular roles of the potent hepatotoxin microcystin (MC) in the bloom-forming cyanobacterium Microcystis. Here, we surveyed transcriptomes of the wild-type strain M. aeruginosa PCC 7806 and the microcystin-deficient ΔmcyB mutant under low light conditions with and without the addition of external MC of the LR variant (MC-LR). Transcriptomic data acquired by microarray and quantitative PCR revealed substantial differences in the relative expression of genes of the central intermediary metabolism, photosynthesis, and energy metabolism. In particular, the data provide evidence for a lower photosystem I (PSI)-to-photosystem II (PSII) ratio and a more pronounced carbon limitation in the microcystin-deficient mutant. Interestingly, only 6% of the transcriptional differences could be complemented by external microcystin-LR addition. This MC signaling effect was seen exclusively for genes of the secondary metabolism category. The orphan polyketide synthase gene cluster IPF38-51 was specifically downregulated in response to external MC-LR under low light. Our data suggest a hierarchical and light-dependent cross talk of secondary metabolites and support both an intracellular and an extracellular role of MC in Microcystis.
University of Potsdam, Institute for Biochemistry and Biology, Department of Microbiology, Potsdam-Golm, Germany.
A Katharina
AK
Makower
University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Department of Aquatic Microbiology, Amsterdam, The Netherlands Netherlands Institute for Ecology, NIOO-KNAW, Department of Aquatic Ecology, Wageningen, The Netherlands.
J Merijn
JM
Schuurmans
University of Potsdam, Institute for Biochemistry and Biology, Department of Bioinformatics, Potsdam-Golm, Germany.
Detlef
D
Groth
Free University of Berlin, Institute of Experimental Physics, Department of Biophysics and Photosynthesis, Berlin, Germany.
Yvonne
Y
Zilliges
University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Department of Aquatic Microbiology, Amsterdam, The Netherlands.
Hans C P
HC
Matthijs
University of Potsdam, Institute for Biochemistry and Biology, Department of Microbiology, Potsdam-Golm, Germany editt@uni-potsdam.de.
Elke
E
Dittmann
D001426:Bacterial Proteins / Q000235:genetics; D017353:Gene Deletion; D020869:Gene Expression Profiling; D053858:Metabolic Networks and Pathways / Q000235:genetics; D046228:Microarray Analysis; D052998:Microcystins / Q000378:metabolism*; D046931:Microcystis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D064210:Secondary Metabolism / Q000187:drug effects
D001426:Bacterial Proteins; D052998:Microcystins; C078588:microcystin