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08:01
LERLIC-MS/MS for In-depth Characterization and Quantification of Glutamine and Asparagine Deamidation in Shotgun Proteomics
Published on: April 9, 2017
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Poly-γ-glutamylation of biomolecules.
Ghader Bashiri1,2, Esther M M Bulloch3,4, William R Bramley3
1School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand. g.bashiri@auckland.ac.nz.
Nature Communications
|February 12, 2024
Summary
Poly-γ-glutamylation adds L-glutamate to cofactor chains, like folates. A bulging substrate model explains how enzymes retain specificity during this processive biopolymerization across species.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- Poly-γ-glutamate tails are crucial for archaeal, bacterial, and eukaryotic cofactors, including folates and F420.
- The precise enzymatic mechanisms for adding glutamates and maintaining cofactor specificity in poly-γ-glutamylation remain largely unknown.
Purpose of the Study:
- To elucidate the mechanism of poly-γ-glutamylation by non-homologous enzymes, folylpolyglutamate synthases and γ-glutamyl ligases.
- To reveal the structural basis for cofactor retention and processive glutamate addition during poly-γ-glutamylation.
Main Methods:
- Enzyme kinetics studies of folylpolyglutamate synthases and γ-glutamyl ligases.
- X-ray crystallography to capture structural snapshots of archaeal γ-glutamyl ligase (CofE) with substrates and products.
Main Results:
- Demonstrated that poly-γ-glutamylation occurs via processive addition of L-glutamate to growing γ-glutamyl chain termini.
- Provided structural evidence of a bulged-chain intermediate, illustrating how the cofactor is retained during chain elongation.
Conclusions:
- Proposed a bulging substrate model for processive poly-γ-glutamylation by terminal extension.
- Highlighted the ubiquitous nature of this mechanism in biopolymerization and its implications for convergent evolution from archaea to humans.
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