Dispersed disease-causing neomorphic mutations on a single protein promote the same localized conformational opening

Area of Science:

• Biochemistry
• Molecular Biology
• Neuroscience

Background:

• Charcot-Marie-Tooth (CMT) disease is a group of inherited peripheral neuropathies.
• Mutations in glycyl-tRNA synthetase (GlyRS) cause an axonal form of CMT, acting as neomorphs with gain-of-function.
• Understanding how dispersed mutations lead to a unified phenotype is crucial.

Purpose of the Study:

• To investigate the structural basis of gain-of-function mutations in GlyRS causing CMT.
• To identify the conformational changes induced by dispersed mutations in GlyRS.
• To explore the role of the WHEP domain in regulating GlyRS structure and function.

Main Methods:

• Hydrogen-deuterium exchange mass spectrometry (HDX-MS) to monitor protein dynamics in solution.
• Small-angle X-ray scattering (SAXS) to determine overall protein structure.
• Analysis of wild-type and mutant GlyRS structures.

Main Results:

• Five spatially dispersed mutations in GlyRS induced the same conformational opening.
• This opening revealed a previously buried consensus area, forming a neomorphic surface.
• The WHEP domain was found to regulate this conformational change, suggesting its loss of function contributes to CMT.

Conclusions:

• Spatially dispersed mutations can converge on a single localized structural effect in GlyRS.
• The identified neomorphic surface is a potential target for therapeutic intervention in CMT.
• The WHEP domain acts as a regulator, and its dysregulation may underlie the gain-of-function in CMT GlyRS mutants.