Structural mechanism of mRNA decoding by mammalian GTPase GTPBP1

Area of Science:

• Molecular Biology
• Structural Biology
• Genetics

Background:

• GTP-binding protein 1 (GTPBP1) is a translational GTPase related to elongation factor eEF1A.
• Loss of GTPBP1 is linked to neurodevelopmental and neurodegenerative disorders.
• GTPBP1's precise molecular functions in translation and quality control remain unclear.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying GTPBP1's function in protein translation.
• To visualize GTPBP1 in complex with the ribosome and aminoacyl-tRNA.
• To understand how GTPBP1 mutations contribute to human diseases.

Main Methods:

• Cryo-electron microscopy (cryo-EM) of mammalian 80S ribosomal complexes.
• Complexes included GTPBP1, aminoacyl-tRNA, and either GTP or GDPCP.

Main Results:

• Distinct GTPBP1 architecture and tRNA interactions were observed.
• Slow GTPBP1 dissociation after GTP hydrolysis was identified, delaying tRNA accommodation.
• This slow dissociation correlates with extended proofreading and higher decoding accuracy.

Conclusions:

• GTPBP1's unique mechanism contributes to accurate translation and potential quality control.
• The structural insights provide a basis for studying GTPBP1 mutations in human diseases.