eIF2B and the Integrated Stress Response: A Structural and Mechanistic View.

Area of Science:

• Molecular Biology
• Neuroscience
• Structural Biology

Background:

• The eukaryotic translation initiation factor 2 (eIF2) forms a ternary complex (TC) with GTP and Met-tRNAi, delivering it to the ribosome.
• The guanine nucleotide exchange factor (GEF) eIF2B regenerates the TC.
• Phosphorylation of eIF2 inhibits eIF2B, triggering the integrated stress response (ISR), which can lead to apoptosis or neuroprotection.

Purpose of the Study:

• To review recent cryo-electron microscopy (cryo-EM) structures of eIF2B.
• To discuss the functional and regulatory mechanisms of eIF2B.
• To explore the therapeutic potential of ISR inhibitors for neurodegenerative disorders.

Main Methods:

• Cryo-electron microscopy (cryo-EM) structural determination.
• Biochemical assays.
• Literature review of recent structural and preclinical data.

Main Results:

• Multiple cryo-EM structures of the nonproductive eIF2B·eIF2(α-P) complex are consistent.
• Significant discrepancies exist between published structures of the productive eIF2B·eIF2 complex.
• Preclinical data support ISR inhibitors as neuroprotective agents.

Conclusions:

• Conflicting structural data for eIF2B·eIF2 necessitate further investigation.
• Understanding eIF2B structure and function is critical for developing therapies for neurodegenerative diseases.
• eIF2B represents a promising therapeutic target for modulating the ISR.