Video Experimental Relacionado

Updated: May 6, 2026

Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses

Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses

Published on: February 26, 2011

El mecanismo estructural de la translocación y la actividad de la helicasa en la ARN polimerasa T7

Y Whitney Yin¹, Thomas A Steitz

¹Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.

|March 16, 2004

Resumen

La ARN polimerasa actúa como un motor molecular. Sus cambios conformacionales, impulsados por la liberación de pirofosfato, permiten la translocación del ADN y la separación de cadenas durante la transcripción.

Área de la Ciencia:

Biología Molecular Biología Molecular
Biología Estructural Biología estructural.
La bioquímica es la bioquímica.

Sus antecedentes:

La ARN polimerasa es un motor molecular esencial para la transcripción.
Comprender su mecanismo requiere una visión estructural detallada de los diferentes estados funcionales.

Objetivo del estudio:

Para aclarar la base estructural de la función de la ARN polimerasa durante la adición y translocación de nucleótidos.
Para investigar el papel de las conformaciones enzimáticas en la separación y translocación de cadenas de ADN.

Principales métodos:

Se utilizó la cristalografía de rayos X para determinar las estructuras de la ARN polimerasa del fag T7.
Se obtuvieron estructuras para el sustrato de la fase de alargamiento y los complejos de productos de pretranslocación.

Principales resultados:

Se identificaron dos conformaciones enzimáticas distintas durante el ciclo de adición de nucleótidos.
Un subdominio de cinco hélices adopta diferentes orientaciones estabilizadas por el nucleósido trifosfato (NTP) o el pirofosfato de producto (PPi) entrantes.
La ausencia de NTP o PPi estabiliza una conformación asociada con la translocación y la separación de cadenas de ADN.

Conclusiones:

La disociación del PPi del producto desencadena un cambio conformacional en la ARN polimerasa.
Este cambio conformacional es crítico para permitir la translocación y la separación de cadenas de ADN.
La ARN polimerasa utiliza distintos estados estructurales para acoplar la energía química al trabajo mecánico en la transcripción.

Más Videos Relacionados

High-throughput Purification of Affinity-tagged Recombinant Proteins

High-throughput Purification of Affinity-tagged Recombinant Proteins

Published on: August 26, 2012

DNA-Tethered RNA Polymerase for Programmable In vitro Transcription and Molecular Computation

DNA-Tethered RNA Polymerase for Programmable In vitro Transcription and Molecular Computation

Published on: December 29, 2021

Videos de Conceptos Relacionados

RNA Structure

RNA Structure

Overview
The basic structure of RNA consists of a five-carbon sugar and one of four nitrogenous bases. Although most RNA is single-stranded, it can form complex secondary and tertiary structures. Such structures play essential roles in the regulation of transcription and translation.
Different Types of RNA Have the Same Basic Structure
There are three main types of ribonucleic acid (RNA): messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). All three RNA types consist of a...

DNA Helicases

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...

Bacterial RNA Polymerase

Bacterial RNA Polymerase

Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...

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:

RNA Structure

RNA Structure

The basic structure of RNA consists of a string of ribonucleotides attached by phosphodiester bonds. Although most RNA is single-stranded, it can form complex secondary and tertiary structures. Such structures play essential roles in the regulation of transcription and translation.
Different Types of RNA Have the Same Basic Structure
There are three main types of ribonucleic acid (RNA) involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). All three...

Mechanism of Conjugation

Mechanism of Conjugation

Bacterial conjugation is a mechanism of horizontal gene transfer that enables the exchange of genetic material between bacterial cells through direct contact. This process is facilitated by a donor cell carrying a conjugative plasmid, which encodes genes necessary for pilus formation, DNA replication, and transfer. The conjugative plasmid plays a central role in initiating and executing the transfer of genetic material.The tra region of the conjugative plasmid encodes proteins responsible for...