Video Experimental Relacionado

Updated: Mar 28, 2026

Strand-Specific Analysis of Proteins at Replicating DNA Strands by Enrichment and Sequencing of Protein-Associated Nascent DNA Method

Strand-Specific Analysis of Proteins at Replicating DNA Strands by Enrichment and Sequencing of Protein-Associated Nascent DNA Method

Published on: May 2, 2025

La ARN polimerasa I propaga la propagación unidireccional de la cromatina silenciosa del ADNr

Stephen W Buck¹, Joseph J Sandmeier, Jeffrey S Smith

¹Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA.

|January 1, 2003

Resumen

En la levadura, el silenciamiento del ADN ribosomal (ADNr) se extiende direccionalmente, lo que requiere la transcripción de la ARN polimerasa I y SIR2. Este proceso limita la recombinación e influye en la vida útil.

Área de la Ciencia:

Biología Molecular Biología Molecular
Genética La genética.
La epigenética es la epigenética.

Sus antecedentes:

Se sabe que el ADN ribosomal (ADNr) en Saccharomyces cerevisiae induce el silenciamiento transcripcional de los genes de la ARN polimerasa II.
Esta represión dependiente de SIR2 (silenciamiento del ADNr) es crucial para limitar la recombinación del ADNr y regular la vida útil.

Objetivo del estudio:

Para investigar la dinámica de propagación y los mecanismos reguladores del silenciamiento del ADNr en la levadura.
Determinar el papel de la transcripción de la ARN polimerasa I (Pol I) en el establecimiento y la direccionalidad del silenciamiento del ADNr.

Principales métodos:

Análisis del silenciamiento de genes y su propagación en secuencias únicas adyacentes.
Monitoreo de la desacetilación de histonas (H3 y H4) correlacionada con la actividad de SIR2.
Investigando el impacto de la sobreexpresión de SIR2 en la propagación del silenciamiento.
Evaluación del requisito de la transcripción de Pol I para el silenciamiento del ADNr.

Principales resultados:

El silenciamiento del ADNr se extiende a secuencias únicas centromero-proximales aguas abajo de la transcripción de Pol I, pero no a secuencias telómero-proximales aguas arriba.
El silenciamiento de la propagación está asociado con la desacetilación de las histonas H3 y H4 dependientes de SIR2 y puede ser mejorado por la sobreexpresión de SIR2.
El silenciamiento del rDNA depende de la transcripción Pol I, y su dirección de propagación está dictada por la dirección de la transcripción Pol I.

Conclusiones:

La transcripción de Pol I juega un papel crítico en el establecimiento de la direccionalidad de la propagación del silenciamiento del ADNr.
Los hallazgos revelan un nuevo mecanismo en el que la transcripción Pol I dicta los límites de silenciamiento epigenético, lo que afecta la estabilidad y la vida útil del ADNr.

Más Videos Relacionados

Studying Ribonucleotide Incorporation: Strand-specific Detection of Ribonucleotides in the Yeast Genome and Measuring Ribonucleotide-induced Mutagenesis

Studying Ribonucleotide Incorporation: Strand-specific Detection of Ribonucleotides in the Yeast Genome and Measuring Ribonucleotide-induced Mutagenesis

Published on: July 26, 2018

Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase

Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase

Published on: April 30, 2010

Videos de Conceptos Relacionados

Spreading of Chromatin Modifications

Spreading 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...

Replication in Eukaryotes

Replication in Eukaryotes

In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high fidelity before cell division, so there are many proteins that fulfill specialized roles in the replication process. Replication occurs in three phases: initiation, elongation, and termination, and ends with two complete sets of chromosomes in the nucleus.
Many Proteins Orchestrate Replication at the Origin
Eukaryotic replication follows many of the same...

Replication in Eukaryotes

Replication in Eukaryotes

Lagging Strand Synthesis

Lagging Strand Synthesis

During replication, the complementary strands in double-stranded DNA are synthesized at different rates. Replication first begins on the leading strand. Replication starts later, occurs more slowly, and proceeds discontinuously on the lagging strand.
There are several major differences between synthesis of the leading strand and synthesis of the lagging strand. 1) Leading strand synthesis happens in the direction of replication fork opening, whereas lagging strand synthesis happens in the...

Bacterial Transcription

Bacterial Transcription

RNA polymerase (RNAP) carries out DNA-dependent RNA synthesis in both bacteria and eukaryotes. Bacteria do not have a membrane-bound nucleus. So, transcription and translation occur simultaneously, on the same DNA template.
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:

The Replisome

The Replisome

DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with...