Related Experiment Video
Updated: Aug 10, 2026
10:59
Atomic Force Microscopy Investigations of DNA Lesion Recognition in Nucleotide Excision Repair
Published on: May 24, 2017
Target DNA chromatinization modulates nicking by L1 endonuclease
G J Cost1, A Golding, M S Schlissel
1Department of Molecular Biology and Genetics and Department of Medicine, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
Nucleic Acids Research
|January 5, 2001
Summary
Human L1 elements are transposons that insert into DNA. Chromatin structure, which packages DNA, generally prevents L1 endonuclease from nicking DNA, but can enhance it for some sequences.
Area of Science:
- Genetics
- Epigenetics
- Molecular Biology
Background:
- L1 elements are abundant human transposons replicating via RNA.
- DNA nicking by L1 endonuclease (L1 EN) is crucial for transposition.
- Genomic DNA exists in chromatin and undergoes various biochemical processes.
Purpose of the Study:
- To investigate how DNA chromatinization affects L1 EN's ability to nick DNA.
- To understand the influence of epigenetic factors on L1 transposition.
Main Methods:
- Examined the effect of substrate chromatinization on L1 EN DNA nicking.
- Assessed L1 EN activity on DNA within nucleosomes.
Main Results:
- DNA incorporated into nucleosomes is generally resistant to L1 EN nicking.
- Nicking of a subset of DNA sequences is paradoxically enhanced within chromatin.
Conclusions:
- Dynamic epigenetic factors like chromatinization significantly influence L1 element placement in the human genome.
- Chromatin structure plays a complex role in regulating L1 transposition efficiency.
Related Concept Videos
02:54Nucleosome Remodeling
Nucleosomes are the basic units of chromatin compaction. Each nucleosome consists of the DNA bound tightly around a histone core, which makes the DNA inaccessible to DNA binding proteins such as DNA polymerase and RNA polymerase. Hence, the fundamental problem is to ensure access to DNA when appropriate, despite the compact and protective chromatin structure.
Nucleosome remodeling complex
Eukaryotic cells have specialized enzymes called ATP-dependent nucleosome remodeling enzymes. These enzymes...
Nucleosome remodeling complex
Eukaryotic cells have specialized enzymes called ATP-dependent nucleosome remodeling enzymes. These enzymes...
02:32Histone Modification
The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
02:25Spreading of Chromatin Modifications
The histone proteins in the nucleosomes are post-translationally modified (PTM) to increase or decrease access to DNA. The commonly observed PTMs are methylation, acetylation, phosphorylation, and ubiquitination of lysine amino acids in the histone H3 tail region. These histone modifications have specific meaning for the cell. Hence, they are called "histone code". The protein complex involved in histone modification is termed as "reader-writer" complex.
Writers
The writer is an enzyme that can...
Writers
The writer is an enzyme that can...
03:17Inheritance of Chromatin Structures
Epigenetics is the study of inherited changes in a cell's phenotype without changing the DNA sequences. It provides a form of memory for the differential gene expression pattern to maintain cell lineage, position-effect variegation, dosage compensation, and maintenance of chromatin structures such as telomeres and centromeres. For example, the structure and location of the centromere on chromosomes are epigenetically inherited. Its functionality is not dictated or ensured by the underlying DNA...
02:41Chromatin Structure Regulates pre-mRNA Processing
In eukaryotic cells, nascent mRNA transcripts need to undergo many post-transcriptional modifications to reach the cell cytoplasm and translate into functional proteins. For a long time, transcription and pre-mRNA processing were considered two independent events that occur sequentially in the cell. However, it has now been well established that transcription and pre-mRNA processing are two simultaneous processes that are precisely regulated inside the cell.
The chromatin structure, especially...
The chromatin structure, especially...
02:36Chromatin Immunoprecipitation- ChIP
Chromatin immunoprecipitation, or ChIP, is an antibody-based technique used to identify sites on DNA that bind to transcription factors of interest or histone proteins. It also helps determine the type of histone modifications such as acetylation, phosphorylation, or methylation.
Types of ChIP
ChIP can be divided into two types - X-ChIP and N-ChIP. X-ChIP involves in vivo cross-linking of histones and regulatory proteins to DNA, fragmenting the DNA by sonication, and isolating the protein-DNA...
Types of ChIP
ChIP can be divided into two types - X-ChIP and N-ChIP. X-ChIP involves in vivo cross-linking of histones and regulatory proteins to DNA, fragmenting the DNA by sonication, and isolating the protein-DNA...