Translocation : movement of tRNA and mRNA through the ribosome / Harry F. Noller.

Format:

Video

Author/Creator:

Noller, Harry F., author.

Language:

English

Subjects (All):

Ribosomes.

Proteins--Synthesis.

Proteins.

Physical Description:

1 streaming video file (41 min.) : digital, mono, SWF file, sound, color

Other Title:

Translocation

Place of Publication:

London : Henry Stewart Talks Ltd, 2008.

System Details:

video file

Summary:

Audio-visual presentation: Ribosomes and translation -- Molecular composition of the ribosome -- Why is the ribosome so big? -- The mRNA channel in the 30S subunit -- Positions of tRNA in the A-, P- and E-sites -- Structural dynamics of the ribosome during translocation -- The hybrid states elongation cycle -- tRNA binding during its movement through the ribosome -- The 70S ribosome -- Distortion of tRNA structure by the ribosome -- The ratchet model -- Cryo-EM experiment -- Inferred relationship between ratcheting and hybrid states -- FRET changes -- Intersubunit movement -- Testing the ratchet model for translocation -- Translocation assay -- What defines the mechanism of translocation -- Sparsomycin -- The energetics of translocation -- E-site tRNA -- The ribosome is a molecular machine.

Contents:

Introduction

Ribosomes and translation

Molecular composition of the ribosome

Why is the ribosome so big?

The ribosome has a big substrate

Crystal structure of the 70S ribosome

The mRNA channel in the 30S subunit

tRNA positions in the A, P & E sites

Location of the tRNA in the ribosome

Positions of A- and P-tRNA in the ribosome

Ribosome structural dynamics during translocation

Positions of tRNA in the ribosome

The hybrid states elongation cycle

States of tRNA binding during movement

Movement of tRNA through the ribosome

Distortion of tRNA structure by the ribosome

tRNA structure distortion by ribosomal P, E sites

The ribosome is a molecular machine

Translocational mechanics: the Ratchet model

The rachet model

tRNA predicted positions in cryo-EM experiment

Inferred relationship - ratcheting, hybrid states

Testing intersubunit movement using FRET

The FRET experiment

FRET experiment results

Changes between S6-L9 and S11-L9

Reversed donor and acceptor fluors

Peptidyl-tRNA deacylation by puromycin reaction

Peptidyl-tRNA deacylation causes rotation

Reaction of a hybrid-state complex with EF-G-GTP

Reversal of intersubunit rotation

Intersubunit movement in single ribosomes

Conclusions from FRET experiments

Testing the ratchet model for translocation

Positions of introduced cysteines in L2 and S6

Juxtaposition of cysteines across subunit interface

Testing the disulfide bridge formation

Disulfide crosslinking prevents subunit dissociation

Identification of the S6-L2 crosslink

Crosslinking prevents polypeptide synthesis

Crosslinked ribosomes (1)

Crosslinked ribosomes (2)

What about translocation?

Translocation assay

Intersubunit crosslinking prevents translocation (1)

Translocation assay (toeprinting)

Intersubunit crosslinking prevents translocation (2)

Relative movement is required for translocation

The strictly EF-G-dependent step of translocation

What defines the mechanism of translocation?

The peptidyl transferase inhibitor sparsomycin

Catalysis of translocation by sparsomycin

The energetics of translocation

tRNA interactions in the 50S E-site

E-tRNA interactions with the ribosome

Exit of the deacylated tRNA from the E-site

The elbow of E-site tRNA stacks on the L1 RNA

Large-scale movement of the L1 arm of 23S rRNA

Movement of 50S subunit in translocation

Acknowledgements

Center for Molecular Biology of RNA.

Notes:

Description based on publisher supplied metadata and other sources.

Retrieved April 16, 2024, from https://hstalks.com/bs/807/.