November 25, 2014
Elucidation of mechanism of metabolism and response to change in light conditions
A joint research team from RIKEN CSRS and Tsukuba University has successfully altered the primary metabolism by metabolic engineering of cyanobacteria.
The research group generated the mutant of the fresh-water cyanobacterium Synechocystis which overexpresses hik8, encoding a histidine kinase related to circadian rhythms. The group measured the metabolite levels and revealed the diminished glycogen levels under light conditions and the increased levels of seven amino acids including glycine and aspartate.
To explain the cause of the metabolite changes, the group also measured the amount of SigE, an RNA polymerase sigma factor, which controls sugar metabolism in this cyanobacterium. SigE proteins were not degraded in the hik8- overexpressing strain under dark conditions. These results indicate that Hik8 controls the primary metabolism via regulating transcriptional regulators related to the sugar metabolism.
These findings open the door to a new way to modify transcription and metabolism in cyanobacteria. Further understanding of molecular mechanisms of signal transduction of cyanobacteria leads to not only progress of basic science but also success of future bioproduction using carbon dioxide and light energy, required for sustainable development avoiding global warming.
Environmental Microbiology doi: 10.1111/1462-2920.12715
T. Osanai, T. Shirai, H. Iijima, A. Kuwahara, I. Suzuki, A. Kondo, MY. Hirai,
"Alteration of cyanobacterial sugar and amino acid metabolism by overexpression hik8, encoding a KaiC-associated histidine kinase".
Takashi Osanai: Research Scientist
Masami Hirai: Team Leader
Metabolic Systems Research Team