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Home Journal Highlights New Insights Into Reduced Circadian Clock of Prochlorococcus
New Insights Into Reduced Circadian Clock of Prochlorococcus Print E-mail

 

The circadian clock of cyanobacteria is different from all other known clocks, consisting of just three proteins which time phosphorylation and dephosphorylation on 24-hour rhythms even in vitro.  axmannThree proteins, Kai's A, B, and C, are thought to control circadian timing in all cyanobacteria. One highly abundant marine cyanobacterium, Prochlorococcus, lacks the gene for KaiA. Now Ilka M. Axmann of Humboldt University, Berlin, Germany, et al. show that the KaiC protein, the major component of the clock, can be phosphorylated at two sites, and remains highly phosphorylated even in the presence of KaiB, the dephosphorylating protein, and in contrast to its analog from other cyanobacteria, does not need KaiA for its phosphorylation. "Thus, the KaiC protein of Prochlorococcus might have compensated for the absence of KaiA in this organism by changing its confirmation so that it becomes highly phosphorylated by default," says Axmann. The mechanism may be similar in purple bacteria, which also lack KaiA, she says. The findings have implications for understanding the mechanism's evolution, as well as potential uses in large scale biotech processes and energy production.  

(I. M. Axmann, U. Dühring, L. Seeliger, A. Arnold, J. T. Vanselow, A. Kramer, and A. Wilde. 2009. Biochemical evidence for a timing mechanism in prochlorococcus. J. Bacteriol. 191:5342-5347.)