Quaternary structure analysis of IRE1

Area of Science:

• Molecular biology
• Cellular signaling
• Protein structure

Background:

• Inositol-requiring enzyme 1 (IRE1) is a type I transmembrane protein crucial for the unfolded protein response.
• IRE1 possesses cytoplasmic kinase and RNase catalytic domains and a luminal domain for sensing unfolded proteins.
• IRE1 activation is mediated by dimerization in the luminal domain, which activates its C-terminal catalytic domain.

Purpose of the Study:

• To investigate the quaternary structures of IRE1.
• To understand the structural basis of IRE1 activation and oligomeric transitions.
• To identify structural features that facilitate or hinder IRE1 functional state changes.

Main Methods:

• Analysis of published crystal structures of IRE1.
• Deduction of quaternary structures based on structural data.
• Computational modeling of protein interfaces and transition energies.

Main Results:

• Two distinct quaternary structures of IRE1 were identified.
• One structure features a large, stable interface requiring significant energy for activation/deactivation.
• The second structure exhibits low dissociation energy, favoring IRE1 oligomeric transitions.

Conclusions:

• IRE1's quaternary structure significantly influences its activation dynamics.
• The low dissociation energy structure is more conducive to the dynamic oligomeric transitions required for IRE1 function.
• Understanding these structures provides insights into the regulation of the unfolded protein response.