陽性・陰性超回転DNAのトルション剛性

P R Selvin¹, D N Cook, N G Pon

¹Department of Physics, University of California, Berkeley.

Science (New York, N.Y.)

|January 3, 1992

まとめ

この研究は,DNAがDNAであることを明らかにしています.

科学分野:

分子生物学は分子生物学である.
バイオフィジックス生物物理学
構造生物学構造生物学とは

背景:

超螺旋的ストレスは,DNAの構造と機能に大きく影響します.
DNAの機械的性質を理解することは,様々な生物学的プロセスにとって極めて重要です.
超巻きDNAへの差分タンパク質結合は,重要な研究分野である.

研究の目的:

異なる超螺旋的張力下でのDNAのトルション定数を定量化するために.
非線形トルションペンデュラムとしてのDNAの機械的振る舞いを調査する.
ポジティブとネガティブに超回転したDNAの柔軟性を比較する.

主な方法:

時間相関単光子カウント技術.
エチジウムブロミドをプローブとして利用する.
pBR322 DNA.のスーパーヘリックス密度範囲で+0.042から-0.123までのトルション定数を測定する.

主要な成果:

DNAは,超螺旋的ストレス下では,結合された非線形トルションペンデュームの振る舞いを示しています.
DNAのハミルトニアンにおけるアンハーモニック項は,室温で約15%である.
陽性超回転DNAは,陰性超回転DNAよりも著しく大きな柔軟性を示しています.

結論:

観察されたDNAの柔軟性の差異は,タンパク質とDNAの相互作用に関する既存のモデルに挑戦しています.
これらの発見は,超螺旋的張力に対するDNAの機械的反応に関する重要な洞察を提供します.
この研究は,DNAの力学とその細胞プロセスへの影響のより深い理解に貢献します.

さらに関連する動画

11:41

Magnetic Tweezers for the Measurement of Twist and Torque

Published on: May 19, 2014

11:27

Studying DNA Looping by Single-Molecule FRET

Published on: June 28, 2014

関連する概念動画

02:05

DNA as a Genetic Template

Two structural features of the DNA molecule provide a basis for the mechanisms of heredity: the four nucleotide bases and its double-stranded nature. The Watson-Crick model of double-helical DNA structure, proposed in 1952, drew heavily upon the X-ray crystallography work of researchers Rosalind Franklin and Maurice Wilkins. Watson, Crick, and Wilkins jointly received the Nobel Prize in Physiology or Medicine for their work in 1962. Franklin was, controversially, excluded from the prize for...

01:02

The DNA Replication Fork

An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork. Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication forks, one in...

00:55

DNA Helicases

DNA unwinding helicase enzymes are a type of motor protein. Motor proteins can translocate along filaments or polymers using energy generated from ATP hydrolysis. Helicases are involved in all the important cellular processes where DNA unwinding is required, such as DNA replication, repair, recombination, and transcription. They are present in all living organisms, but vary in their structure, function, and mechanism of action. For example, in prokaryotes, DnaB helicase binds and translocates...

02:02

DNA Topoisomerases

Topoisomerases are enzymes that relax overwound DNA molecules during various cell processes, including DNA replication and transcription. These enzymes regulate positive and negative DNA supercoiling without changing the nucleotide sequence. DNA overwinding in a clockwise direction results in positively supercoiled DNA, whereas underwinding in a counterclockwise direction produces negatively supercoiled DNA.
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...

01:03

Single-Strand DNA Binding Proteins

For successful DNA replication, the unwinding of double-stranded DNA must be accompanied by stabilization and protection of the separated single strands of the DNA. This crucial task is performed by single-strand DNA-binding (SSB) proteins. They bind to the DNA in a sequence-independent manner, which means that the nitrogenous bases of the DNA need not be present in a specific order for binding of SSB proteins to it. The binding of SSB proteins straightens single-stranded DNA (ssDNA) and makes...