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Related Concept Videos

Circadian Rhythms and Gene Regulation02:19

Circadian 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,...
Circadian Rhythms and Gene Regulation02:19

Circadian 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,...
Biological Clocks and Seasonal Responses02:45

Biological 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.
Prokaryotic Transcriptional Activators and Repressors01:58

Prokaryotic Transcriptional Activators and Repressors

The organization of prokaryotic genes in their genome is notably different from that of eukaryotes. Prokaryotic genes are organized, such that the genes for proteins involved in the same biochemical process or function are located together in groups. This group of genes, along with their regulatory elements, are collectively known as an operon. The functional genes in an operon are transcribed together to give a single strand of mRNA known as polycistronic mRNA.
Transcription of prokaryotic...
Prokaryotic Transcriptional Activators and Repressors01:58

Prokaryotic Transcriptional Activators and Repressors

The organization of prokaryotic genes in their genome is notably different from that of eukaryotes. Prokaryotic genes are organized, such that the genes for proteins involved in the same biochemical process or function are located together in groups. This group of genes, along with their regulatory elements, are collectively known as an operon. The functional genes in an operon are transcribed together to give a single strand of mRNA known as polycistronic mRNA.
Transcription of prokaryotic...
Transcription Attenuation in Prokaryotes02:42

Transcription Attenuation in Prokaryotes

Transcriptional attenuation occurs when RNA transcription is prematurely terminated due to the formation of a terminator mRNA hairpin structure.  Bacteria use these hairpins to regulate the transcription process and control the synthesis of several amino acids including histidine, lysine, threonine, and phenylalanine. Transcription attenuation takes place in the non-coding regions of mRNA.
There are several different mechanisms used to attenuate transcription. In ribosome mediated...

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Rapid Analysis of Circadian Phenotypes in Arabidopsis Protoplasts Transfected with a Luminescent Clock Reporter
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Circadian clock proteins in prokaryotes: hidden rhythms?

Maria Loza-Correa1, Laura Gomez-Valero, Carmen Buchrieser

  • 1Institut Pasteur, Unité de Biologie des Bactéries Intracellulaires Paris, France.

Frontiers in Microbiology
|June 21, 2011
PubMed
Summary

Circadian clock genes, like kaiA, kaiB, and kaiC, are found in prokaryotes, including Cyanobacteria. Their evolution involves lateral gene transfer, with conserved functions noted in bacteria like Legionella pneumophila.

Keywords:
Legionellaarcheacircadian clock genescyanobacteriaevolutionproteobacteria

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Area of Science:

  • Microbiology
  • Molecular Biology
  • Evolutionary Biology

Background:

  • Circadian clocks are essential for eukaryotic adaptation to daily and seasonal cycles.
  • Prokaryotic circadian clock mechanisms, particularly in Cyanobacteria regulated by kaiA, kaiB, and kaiC genes, are well-established.
  • The presence and function of these genes in other prokaryotes remain less understood.

Purpose of the Study:

  • To review the circadian system in cyanobacteria.
  • To provide an overview and phylogenetic analysis of prokaryotic organisms possessing key circadian genes (kaiA, kaiB, kaiC).
  • To explore the evolutionary history and potential functions of these genes in diverse prokaryotes.

Main Methods:

  • Literature review of circadian clock mechanisms in prokaryotes.
  • Phylogenetic analysis of kai gene distribution and conservation.
  • Comparative analysis of KaiC protein sequences and functional residues.

Main Results:

  • The kai genes in prokaryotes have undergone evolution influenced by lateral gene transfer.
  • Cyanobacteria possess a well-characterized circadian system regulated by kaiA, kaiB, and kaiC.
  • Legionella pneumophila contains kaiB and kaiC, with conserved functional residues in KaiC, suggesting potential roles.

Conclusions:

  • The evolutionary path of kai genes is complex, involving horizontal gene transfer, necessitating further in-depth research.
  • The presence of conserved kai genes in bacteria like L. pneumophila highlights potential, yet uncharacterized, circadian functions.
  • Understanding the evolution and function of prokaryotic circadian clock genes is crucial for deciphering their biological significance.