In Vitro Cross-Linking MS Reveals SMG1-UPF2-SMG7 Assembly as Molecular Partners within the NMD Surveillance

Area of Science:

• Molecular Biology
• Biochemistry
• Genetics

Background:

• Aberrant mRNAs with premature stop codons cause genetic diseases and cancers.
• The nonsense-mediated mRNA decay (NMD) pathway degrades these aberrant mRNAs, preventing truncated protein synthesis.

Purpose of the Study:

• To investigate protein-protein interactions (PPIs) within the NMD machinery using chemical cross-linking mass spectrometry (CLMS).
• To identify novel interaction networks and structural insights within the NMD pathway.

Main Methods:

• Utilized chemical cross-linking mass spectrometry (CLMS) to map protein-protein interactions.
• Analyzed interactions between UPF2, SMG1, and SMG7 within the NMD pathway.
• Modeled protein structures to visualize interaction interfaces.

Main Results:

• Identified novel complex networks between UPF2, SMG1, and SMG7, with UPF2 acting as a bridge.
• UPF2's N-terminal and MIF4G domains interact with SMG7 and SMG1, respectively.
• Cancer-derived mutations in UPF2 or SMG1 PPIs significantly affect structural stability.

Conclusions:

• The study elucidates the protein-protein interface of SMG1, UPF2, and SMG7, offering potential therapeutic targets.
• Modulating the NMD pathway could enhance neoantigen production for cancer vaccine development.