サイアノバクテリアの昼間フィードバックプロセスとしてkaiABC遺伝子クラスタの発現
1Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan. ishiura@bio.nagoya-u.ac.jp
まとめ
サイアノバクテリアは,KaiABC遺伝子群によって調節される昼夜時計を持っています. KaiCのネガティブなフィードバックは振動を生じ,KaiAはこれらの単純な生物でこの生物学的リズムを維持します.
科学分野:
- 微生物学 微生物学とは
- 分子生物学は分子生物学である.
- クロノバイオロジー クロノバイオロジー
背景:
- サイアノバクテリアは,日中時計を示す最も単純な生物として知られています.
- KaiABC遺伝子クラスターは,サイアノバクテリアの昼間時計のメカニズムの中心にある.
研究 の 目的:
- サイアノバクテリアの昼夜リズムにおけるKaiABC遺伝子の役割を調査する.
- サイアノバクテリアの昼間振動の基礎にある規制メカニズムを解明する.
主な方法:
- シネココックスのKaiABC遺伝子クラスタのクローン.
- KaiA,KaiB,およびKaiC遺伝子のクロック変異のマッピング.
- 異なる遺伝子発現条件下でのプロモーター活動とmRNAサイクルの分析.
主要な成果:
- KaiABC遺伝子内で19のクロック突然変異が特定されました.
- KaiAとKaiBのプロモーター活動とKaiAとKaiBCのmRNAレベルは昼夜リズムを示した.
- カイ遺伝子の不活性化または過剰発現は,昼夜リズムとプロモーターの活動を変化させ,その調節的役割を示唆した.
結論:
- KaiC発現とKaiCタンパク質を伴うネガティブなフィードバックループは,昼間の振動を生成します.
- KaiAタンパク質は,KaiCの発現を高め,昼間の振動を維持する.
- KaiABCシステムは,サイアノバクテリアの昼間時計の基本的メカニズムを表しています.
関連する概念動画
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 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 of prokaryotic...
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 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,...
Coordination of Gene Expression Processes in Bacteria
The DNA replication, transcription, and translation processes are intricately coupled in bacteria, allowing efficient gene expression and rapid protein synthesis. While this physical and functional coordination is advantageous, it introduces challenges that bacteria overcome through specific regulatory mechanisms.Coupling of Replication, Transcription, and TranslationThe coupling of replication, transcription, and translation is a hallmark of bacterial gene expression. As the replisome unwinds...
Global Regulatory Systems
Global regulatory systems in bacteria enable rapid and coordinated responses to environmental changes by integrating sensory inputs with gene expression, ensuring efficient adaptation to fluctuating conditions. Key global regulatory mechanisms include regulons, two-component systems, sigma factors, and secondary messengers.Regulons and Global RegulatorsA regulon is a collection of genes and operons controlled by a common global regulator. These regulators enable bacteria to prioritize resource...


