Related Experiment Video
Updated: Jun 4, 2026
05:44
Monitoring Circadian Oscillations with a Bioluminescence Reporter in Organoids
Published on: February 16, 2024
The cyanobacterial circadian system: from biophysics to bioevolution
Carl Hirschie Johnson1, Phoebe L Stewart, Martin Egli
1Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA. carl.h.johnson@vanderbilt.edu
Annual Review of Biophysics
|February 22, 2011
Summary
Cyanobacteria
Area of Science:
- Molecular biology
- Biochemistry
- Structural biology
Background:
- Cyanobacteria possess a biological clock controlling gene expression and chromosome topology.
- The circadian system involves a posttranslational oscillator (PTO) and a transcriptional/translational feedback loop (TTFL).
Purpose of the Study:
- To elucidate the molecular mechanisms of the cyanobacterial circadian clock.
- To understand the role of KaiA, KaiB, and KaiC proteins in circadian timekeeping.
Main Methods:
- In vitro reconstitution of the PTO using purified KaiA, KaiB, and KaiC proteins and ATP.
- High-resolution structural analysis of circadian proteins.
- Biophysical and biochemical approaches to study oscillator function.
Main Results:
- The PTO can be reconstituted in vitro, demonstrating its core function.
- Key phosphorylations of KaiC are associated with circadian phase.
- Structural data illuminate the unidirectional mechanism of the KaiABC oscillator.
Conclusions:
- The cyanobacterial circadian clock, particularly the KaiABC oscillator, provides a fundamental model for biological timekeeping.
- Understanding this system offers insights into circadian clocks in higher organisms, including mammals.
Related Concept Videos
02:19Circadian Rhythms and Gene Regulation
The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent years,...
02:19Circadian Rhythms and Gene Regulation
The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent years,...
02:45Biological Clocks and Seasonal Responses
The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.
01:15Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response
Circadian rhythms are cyclic changes that are crucial in plasma drug concentrations. Various standard circadian parameters, including core body temperature, heart rate, and other cardiovascular factors, directly impact disease states and the therapeutic response to drug therapy.
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
01:30Bacterial Phylum Cyanobacteria
Cyanobacteria are a diverse group of oxygenic, phototrophic bacteria that played a pivotal role in converting Earth’s atmosphere from anoxic to oxygen-rich billions of years ago. They exhibit remarkable morphological diversity, ranging from unicellular forms to filamentous types, with cell sizes varying between 0.5 μm and 100 μm. Cyanobacteria are classified into five groups: Chroococcales (unicellular, dividing by binary fission), Pleurocapsales (unicellular, dividing by multiple fission),...