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New moonlighting activities for various GroEL/Hsp60 proteins, mainly characterized using recombinant M. tuberculosis
Zhiyu Zhou1, Dong Yang1, Isaline Lambert2
1Microbiology, Bioorganic and Macromolecular Chemistry Unit, Faculty of Pharmacy, Université libre de Bruxelles (ULB), Boulevard du Triomphe, CP205/2, 1050, Brussels, Belgium.
International Journal of Biological Macromolecules
|November 30, 2025
Summary
Group I chaperonins, like M. tuberculosis GroEL1, possess unexpected thioesterase activity. This discovery reveals new roles in protein modification and potential links to antibiotic resistance.
Area of Science:
- Biochemistry
- Molecular Biology
- Microbiology
Background:
- Group I chaperonins are essential for protein folding and cellular processes.
- M. tuberculosis GroEL1 is a key chaperonin in this pathogen.
Purpose of the Study:
- To investigate the enzymatic activities of M. tuberculosis GroEL1 beyond protein folding.
- To explore the potential role of GroEL1 in M. tuberculosis pathogenesis.
Main Methods:
- Recombinant expression and purification of various chaperonins (E. coli GroEL, human Hsp60, M. tuberculosis GroEL1 and GroEL2).
- Enzyme activity assays including thioesterase, esterase, and auto-acyltransferase.
- Site-directed mutagenesis to identify key residues for thioesterase activity.
- Analysis of substrate specificity and oligomeric state effects.
- In vitro assays for PpsE palmitoylation.
Main Results:
- M. tuberculosis GroEL1, GroEL2, E. coli GroEL, and human Hsp60 exhibit thioesterase activity.
- GroEL1 and GroEL2 also possess esterase and auto-acyltransferase activities.
- Smaller oligomers of Hsp60 and GroEL1 utilized long-chain acyl substrates like palmitoyl-CoA.
- Specific residues (Asp86, Thr89, Ser393) in GroEL1 are crucial for its thioesterase activity.
- GroEL1 enhances palmitoylation of PpsE, a protein involved in PDIM biosynthesis.
Conclusions:
- M. tuberculosis GroEL1 has novel enzymatic functions beyond protein folding, including thioesterase, esterase, and auto-acyltransferase activities.
- These activities, particularly PpsE palmitoylation, may contribute to M. tuberculosis virulence and antibiotic resistance via PDIM biosynthesis.
