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X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
Published on: May 13, 2020
Structural characterization of the principal mRNA-export factor Mex67-Mtr2 from Chaetomium thermophilum
Shintaro Aibara1, Eugene Valkov1, Meindert H Lamers1
1MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge CB2 0QH, England.
Abstract:
Members of the Mex67-Mtr2/NXF-NXT1 family are the principal mediators of the nuclear export of mRNA. Mex67/NXF1 has a modular structure based on four domains (RRM, LRR, NTF2-like and UBA) that are thought to be present across species, although the level of sequence conservation between organisms, especially in lower eukaryotes, is low. Here, the crystal structures of these domains from the thermophilic fungus Chaetomium thermophilum are presented together with small-angle X-ray scattering (SAXS) and in vitro RNA-binding data that indicate that, not withstanding the limited sequence conservation between different NXF family members, the molecules retain similar structural and RNA-binding properties. Moreover, the resolution of crystal structures obtained with the C. thermophilum domains was often higher than that obtained previously and, when combined with solution and biochemical studies, provided insight into the structural organization, self-association and RNA-binding properties of Mex67-Mtr2 that facilitate mRNA nuclear export.
Insights
The Mex67-Mtr2/NXF-NXT1 complex exports mRNA from the nucleus. Despite low sequence conservation, its domains from Chaetomium thermophilum retain similar structures and RNA-binding properties, aiding mRNA export.
Area of Science:
- Molecular Biology
- Structural Biology
- Mycology
Background:
- The Mex67-Mtr2/NXF-NXT1 complex is crucial for mRNA nuclear export.
- This complex comprises four domains (RRM, LRR, NTF2-like, UBA), conserved across species.
- Sequence conservation of NXF family members is low, particularly in lower eukaryotes.
Purpose of the Study:
- To determine the crystal structures of Mex67-Mtr2 domains from the thermophilic fungus Chaetomium thermophilum.
- To investigate the structural organization, self-association, and RNA-binding properties of the Mex67-Mtr2 complex.
- To understand how these properties facilitate mRNA nuclear export.
Main Methods:
- X-ray crystallography to obtain high-resolution structures of C. thermophilum Mex67-Mtr2 domains.
- Small-angle X-ray scattering (SAXS) to study molecular shape and size in solution.
- In vitro RNA-binding assays to assess complex-RNA interactions.
- Biochemical studies to analyze self-association and structural organization.
Main Results:
- High-resolution crystal structures of C. thermophilum Mex67-Mtr2 domains were determined.
- SAXS and RNA-binding data revealed conserved structural and functional properties despite low sequence homology.
- The study provided insights into the structural basis of Mex67-Mtr2 self-association and RNA binding.
Conclusions:
- The Mex67-Mtr2 complex maintains conserved structural and RNA-binding functions for mRNA export, even with limited sequence conservation.
- Structural insights from C. thermophilum provide a model for understanding mRNA nuclear export mechanisms.
- The findings highlight the adaptability and conserved function of essential molecular machinery across diverse organisms.
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