Video Experimental Relacionado

Updated: May 24, 2025

Analysis of LINE-1 Retrotransposition at the Single Nucleus Level

Analysis of LINE-1 Retrotransposition at the Single Nucleus Level

Published on: April 23, 2016

Mecanismo estructural de la transcripción inversa basada en objetivos de LINE-1

George E Ghanim¹, Hongmiao Hu¹, Jerome Boulanger¹

¹MRC Laboratory of Molecular Biology, Cambridge, UK.

Science (New York, N.Y.)

|March 6, 2025

Resumen

Los retrotransposones del elemento intercalado largo humano-1 (LINE-1) utilizan transcripción inversa dirigida al objetivo (TPRT). Las estructuras cryo-EM revelan la dinámica de ORF2p y la remodelación del ADN, descubriendo cómo factores como PCNA regulan la retrotransposición LINE-1.

Área de la Ciencia:

Biología molecular
La genética
Biología estructural

Sus antecedentes:

El elemento intercalado largo-1 (LINE-1) son retrotransposones autónomos activos en el genoma humano.
Los elementos LINE-1 se propagan a través de la transcripción inversa de su ARNm.
La comprensión de los mecanismos de retrotransposición LINE-1 es crucial para la estabilidad del genoma.

Objetivo del estudio:

Elucidar los mecanismos estructurales de la transcripción inversa primada por el objetivo (TPRT) en humanos.
Para revelar la dinámica conformacional de la proteína LINE-1 ORF2 (ORF2p) durante la TPRT.
Identificar las funciones reguladoras de los factores de acogida en la retrotransposición LINE-1.

Principales métodos:

Cuatro estructuras de microscopía cryoelectrónica (cryo-EM) del complejo TPRT humano LINE-1.
Análisis de los cambios conformacionales de ORF2p y remodelación del ADN objetivo.
Pronóstico basado en la estructura de los sitios de unión para los factores asociados a LINE-1.

Principales resultados:

Se determinaron las estructuras detalladas del complejo TPRT LINE-1 humano.
ORF2p sufre cambios conformacionales significativos y remodela el ADN objetivo para la iniciación de TPRT.
Durante la transcripción inversa de la primera hebra se observó el desprendimiento de la segunda hebra de ADN.
Se identificaron sitios de unión de alta confianza para PCNA y PABPC1 en ORF2p.

Conclusiones:

Los datos estructurales proporcionan información sobre el mecanismo de inicio de la TPRT LINE-1.
Es probable que los factores huésped PCNA y PABPC1 regulen la retrotransposición de LINE-1 a través de la unión de ORF2p.
Este trabajo apoya un modelo mecanicista para los resultados de retrotransposición LINE-1 en células.

Más Videos Relacionados

Detection of Retrotransposition Activity of Hot LINE-1s by Long-Distance Inverse PCR

Detection of Retrotransposition Activity of Hot LINE-1s by Long-Distance Inverse PCR

Published on: July 27, 2019

Determining 3'-Termini and Sequences of Nascent Single-Stranded Viral DNA Molecules during HIV-1 Reverse Transcription in Infected Cells

Determining 3'-Termini and Sequences of Nascent Single-Stranded Viral DNA Molecules during HIV-1 Reverse Transcription in Infected Cells

Published on: January 30, 2019

Videos de Conceptos Relacionados

Non-LTR Retrotransposons

Non-LTR Retrotransposons

As the name suggests, non-LTR retrotransposons lack the long terminal repeats characteristic of the LTR retrotransposons. Additionally, both LTR and non-LTR retrotransposons use distinct mechanisms of mobilization. Non-LTR retrotransposons are further divided into two classes - Long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs), both of which occur abundantly in most mammals, including humans. Some of the active non-LTR retrotransposons in humans are L1...

LTR Retrotransposons

LTR Retrotransposons

LTR retrotransposons are class I transposable elements with long terminal repeats flanking an internal coding region. These elements are less abundant in mammals compared to other class I transposable elements. About 8 percent of human genomic DNA comprises LTR retrotransposons. Some of the common examples of LTR retrotransposons are Ty elements in yeast and Copia elements in Drosophila.
The internal coding region of LTR retrotransposons and their mechanism of transposition closely resembles a...

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:

Transcription Initiation

Transcription Initiation

Initiation is the first step of transcription in eukaryotes. Prokaryotic RNA Polymerase (RNAP) can bind to the template DNA and start transcribing. On the other hand, transcription in eukaryotes requires additional proteins, called transcription factors, to first bind to the promoter region in the DNA template. This binding helps recruit the specific RNAP that can assemble on the DNA and start transcription.
The promoters and enhancers and their accessory proteins allow tight regulation of...

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...

Retrovirus Life Cycles

Retrovirus Life Cycles

Retroviruses have a single-stranded RNA genome that undergoes a special form of replication. Once the retrovirus has entered the host cell, an enzyme called reverse transcriptase synthesizes double-stranded DNA from the retroviral RNA genome. This DNA copy of the genome is then integrated into the host’s genome inside the nucleus via an enzyme called integrase. Consequently, the retroviral genome is transcribed into RNA whenever the host’s genome is transcribed, allowing the...