Related Experiment Video
Updated: Jul 18, 2026
10:13
Simple and Fast Rolling Circle Amplification-Based Detection of Topoisomerase 1 Activity in Crude Biological Samples
Published on: December 2, 2022
Type IA topoisomerases: a simple puzzle?
Thierry Viard1, Claire Bouthier de la Tour
1Nicholas Cozzarelli Laboratory, Molecular and Cell Biology Department, 16 Barker Hall, University of California, Berkeley, CA 94720-3204, USA. viard@berkeley.edu
Biochimie
|December 5, 2006
Summary
Type IA topoisomerases are essential enzymes modifying DNA topology across all life. Their structure includes a core domain and a variable carboxyl-terminal domain interacting with proteins to form "toposomes," influencing enzymatic activity and evolution.
Area of Science:
- Biochemistry
- Molecular Biology
- Evolutionary Biology
Background:
- Type IA topoisomerases are enzymes crucial for managing DNA topology.
- These enzymes are conserved across all domains of life, including bacteria, archaea, and eukaryotes.
- They possess a two-domain structure: a conserved core domain and a variable carboxyl-terminal domain.
Purpose of the Study:
- To review the structure and function of Type IA topoisomerases.
- To discuss the evolutionary significance of the topoisomerase-cofactor complex, or "toposome".
- To explore the enzymatic consequences of this complex.
Main Methods:
- Literature review of Type IA topoisomerase research.
- Analysis of protein domain structures and functions.
- Discussion of evolutionary conservation and cofactor interactions.
Main Results:
- Type IA topoisomerases consist of a catalytic core and a variable C-terminal domain.
- The C-terminal domain mediates interactions with other proteins, forming functional "toposomes".
- These complexes are vital for defining the physiological roles of topoisomerase activity.
Conclusions:
- The topoisomerase-cofactor complex ("toposome") has significant evolutionary relevance.
- Understanding these complexes provides insight into the enzymatic consequences of DNA topology modification.
- Type IA topoisomerases and their associated cofactors are fundamental to cellular processes across life.
More Related Videos
Related Concept Videos
02:02DNA 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...
Types and Mechanism of action
Topoisomerases are divided into two main types. Type I...
00:55DNA 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...
02:53Conservative Site-specific Recombination and Phase Variation
Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
The recognition sites for Cre recombinase called LoxP...
The recognition sites for Cre recombinase called LoxP...
01:19Allosteric Proteins-ATCase
Binding sites linkages can regulate a protein's function. For example, enzyme activity is often regulated through a feedback mechanism where the end product of the biochemical process serves as an inhibitor.
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
02:37Restarting Stalled Replication Forks
DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart, a...
01:48ATP Synthase: Mechanism
In animals, the mitochondrial F1F0 ATP synthase is the key protein that synthesizes ATP molecules through a complex catalytic mechanism. While the nuclear genome encodes the majority of ATP synthase subunits, the mitochondrial genome encodes some of the enzyme's most critical components. The formation of this multi-subunit enzyme is a complex multi-step process regulated at the level of transcription, translation, and assembly. Defects in one or more of these steps can result in decreased ATP...