Related Experiment Video
Updated: May 2, 2026
Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses
Published on: February 25, 2011
SAXS analysis of the tRNA-modifying enzyme complex MnmE/MnmG reveals a novel interaction mode and GTP-induced
Marcus Fislage1, Elke Brosens1, Egon Deyaert1
1Structural Biology Research Center, VIB, Pleinlaan 2, 1050 Brussel, Belgium Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel, Belgium.
Abstract:
Transfer ribonucleic acid (tRNA) modifications, especially at the wobble position, are crucial for proper and efficient protein translation. MnmE and MnmG form a protein complex that is implicated in the carboxymethylaminomethyl modification of wobble uridine (cmnm(5)U34) of certain tRNAs. MnmE is a G protein activated by dimerization (GAD), and active guanosine-5'-triphosphate (GTP) hydrolysis is required for the tRNA modification to occur. Although crystal structures of MnmE and MnmG are available, the structure of the MnmE/MnmG complex (MnmEG) and the nature of the nucleotide-induced conformational changes and their relevance for the tRNA modification reaction remain unknown. In this study, we mainly used small-angle X-ray scattering to characterize these conformational changes in solution and to unravel the mode of interaction between MnmE, MnmG and tRNA. In the nucleotide-free state MnmE and MnmG form an unanticipated asymmetric α2β2 complex. Unexpectedly, GTP binding promotes further oligomerization of the MnmEG complex leading to an α4β2 complex. The transition from the α2β2 to the α4β2 complex is fast, reversible and coupled to GTP binding and hydrolysis. We propose a model in which the nucleotide-induced changes in conformation and oligomerization of MnmEG form an integral part of the tRNA modification reaction cycle.
Insights
Transfer RNA (tRNA) modifications are vital for protein translation. The MnmE/MnmG complex undergoes significant structural changes upon guanosine-5'-triphosphate (GTP) binding, influencing tRNA modification.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Transfer RNA (tRNA) modifications, particularly at the wobble position, are essential for accurate protein synthesis.
- The MnmE and MnmG proteins form a complex (MnmEG) responsible for modifying wobble uridine (cmnm(5)U34) in specific tRNAs.
- MnmE functions as a GTPase, requiring GTP hydrolysis for its activity in tRNA modification.
Purpose of the Study:
- To elucidate the structure of the MnmE/MnmG complex (MnmEG) in solution.
- To investigate nucleotide-induced conformational changes in MnmEG.
- To understand the interaction mechanism between MnmEG and tRNA.
Main Methods:
- Small-angle X-ray scattering (SAXS) was employed to study MnmEG conformational dynamics in solution.
- SAXS was used to analyze the interactions between MnmEG and tRNA.
- Biochemical assays were utilized to study GTP binding and hydrolysis.
Main Results:
- In the absence of nucleotides, MnmEG forms an unexpected asymmetric α2β2 complex.
- GTP binding induces oligomerization of MnmEG, transitioning to an α4β2 complex.
- This structural transition is rapid, reversible, and linked to GTP binding and hydrolysis.
Conclusions:
- Nucleotide-dependent conformational and oligomerization changes in MnmEG are integral to the tRNA modification process.
- The study provides a model for how MnmEG structural dynamics facilitate tRNA modification.
- Understanding MnmEG complex dynamics offers insights into the regulation of protein translation.
More Related Videos
08:55Characterization of Multi-subunit Protein Complexes of Human MxA Using Non-denaturing Polyacrylamide Gel-electrophoresis
Published on: October 28, 2016
11:27X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
Published on: May 13, 2020
Related Concept Videos
02:26tRNA Activation
02:53Ribosomal RNA Synthesis
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
02:36Transfer RNA Synthesis
Each of these chemical modifications is carried by a specific enzyme, post-transcription. All of these enzymes have unique base and site-specificity. Methylation, the most common chemical modification, is carried by at least nine different enzymes, with...
01:45Tail-anchoring of Proteins in the ER Membrane
01:19RNA Structure
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...
01:23RNA Structure
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...