Metabolic rhythms of unicellular, nitrogen fixing cyanobacteria and possible interplay with modeled KaiABC circadian oscillator
Červený, Jan ; Nedbal, Ladislav Typ dokumentu: Postery Konference/Akce: Molecular Bioenergetics of Cyanobacteria : from Cell to Community, Sant Feliu de Guixols (Spain), 2011-04-10 / 2011-04-15
Abstrakt: Circadian clocks of living organisms provide evolutionary advantage and make living in dynamic environment more efficient. The clocks affect human lives and health as well as control the simplest organisms such as prokaryotic cyanobacteria. The cyanobacteria represent an excellent model that is amendable to a multitude of genetic, biochemical, and biophysical methods. The cyanobacterium, Cyanothece sp. ATCC 51142 relies on the circadian clock to permit, in the same cell, anoxygenic nitrogen fixation at night and oxygenic photosynthesis during solar day. We measured real-time, in-situ photosynthetic and respiratory activities as well as the culture growth under light forcing conditions and also under constant light, i.e. free-running mode. Interestingly, the experiments show a strong 24h-period dynamic pattern that is replaced by apparent 12h-period in free running mode. The 24h-pattern does not change significantly when changing the light/dark ratio from 16hL/8hD to 12hL/12hD and 8hL/16hD. Furthermore, we tried to elucidate connection between these metabolic rhythms and known structure of KaiABC circadian oscillator by means of mathematical modeling. One of simulation results show a strong correlation between the presumed catabolic event indicated by significant peak in respiratory activity, and simulated dynamics of KaiB4 complex in modeled circadian pacemaker. A causal relationship between these 2 events is suggested because KaiB4 facilitates dephosphorylation of KaiC6 hexamer, which is known to signal upcoming dark period.
dusík; oscilátory; sinice; ciardian oscillator; cyanophyta; KaiABC; metabolic rhytms; nitrogen; nitrogen fixing; oscillators Citace: Červený J., Nedbal L.: Molecular Bioenergetics of Cyanobacteria: From Cell to Community, Sant Feliu de Guixols, 10-15 April 2011
Práva: Dílo je chráněno podle autorského zákona č. 121/2000 Sb.; Licence Creative Commons Uveďte autora 3.0 Česko
Instituce: Ústav výzkumu globální změny AV ČR