![]() ![]() ![]() They identified a single mutation in the gene for RpaA that reduces the protein’s DNA-binding efficiency. The researchers also used the in vitro system to explore the genetic origins of clock disruption in an arrhythmic strain of cyanobacteria. This system enabled the team to determine how SasA and CikA enhance the robustness of the oscillator, keeping it ticking under conditions in which the KaiABC proteins by themselves would stop oscillating. Using fluorescent labeling techniques, the researchers were able to track the interactions between all of these clock components as the whole system oscillates with a circadian rhythm for many days and even weeks. “In cyanobacteria, this rhythmic binding and unbinding at over 100 different sites in their genome activates and deactivates the expression of numerous genes important to health and survival.” “SasA and CikA respectively activate and deactivate RpaA such that it rhythmically binds and unbinds DNA,” LiWang explained. The new in vitro clock includes, in addition to the oscillator proteins, two kinase proteins (SasA and CikA), whose activities are modified by interacting with the oscillator, as well as a DNA-binding protein (RpaA) and its DNA target. In living cells, signals from the oscillator are transmitted through other proteins to control the expression of genes in a circadian cycle. The oscillator consists of three related proteins: KaiA, KaiB, and KaiC. The new study builds on previous work by Japanese researchers, who in 2005 reconstituted the cyanobacterial circadian oscillator, the basic 24-hour timekeeping loop of the clock. The interior of live cells is highly complex, in stark contrast to the much simpler conditions in vitro,” said Andy LiWang, professor of chemistry and biochemistry at UC Merced and a corresponding author of the paper. “These results were so surprising because it is common to have results in vitro that are somewhat inconsistent with what is observed in vivo. The team conducted experiments in living cells to confirm that their in vitro results are consistent with the way the clock operates in live cyanobacteria. ![]() Having a functioning clock that can be studied in the test tube (“in vitro”) instead of in living cells (“in vivo”) provides a powerful platform for exploring the clock’s mechanisms and how it responds to changes. Partch noted that the molecular details of circadian clocks are remarkably similar from cyanobacteria to humans. “Reconstituting a complicated biological process like the circadian clock from the ground up has really helped us learn how the clock proteins work together and will enable a much deeper understanding of circadian rhythms,” said Carrie Partch, professor of chemistry and biochemistry at UC Santa Cruz and a corresponding author of the study. Researchers in three labs at UC Santa Cruz, UC Merced, and UC San Diego collaborated on the study, published October 8 in Science. The cyclical interactions of clock proteins keep the biological rhythms of life in tune with the daily cycle of night and day, and this happens not only in humans and other complex animals but even in simple, single-celled organisms such as cyanobacteria.Ī team of scientists has now reconstituted the circadian clock of cyanobacteria in a test tube, enabling them to study rhythmic interactions of the clock proteins in real time and understand how these interactions enable the clock to exert control over gene expression. Daily cycles in virtually every aspect of our physiology are driven by biological clocks (also called circadian clocks) in our cells. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |