Function and structure of a prokaryotic formylglycine-generating enzyme

Area of Science:

• Biochemistry
• Structural Biology
• Microbiology

Background:

• Type I sulfatases require post-translational modification for activity.
• Eukaryotic sulfatases are activated by formylglycine-generating enzyme (FGE) oxidizing a cysteine residue.
• Sulfatase activation machinery in prokaryotes remains largely uncharacterized.

Purpose of the Study:

• To identify and characterize a prokaryotic formylglycine-generating enzyme (FGE).
• To elucidate the structural and catalytic mechanisms of prokaryotic FGE.
• To investigate the role of FGE in sulfatase activation in Mycobacterium tuberculosis.

Main Methods:

• Identification of a prokaryotic FGE homolog in Mycobacterium tuberculosis.
• Crystallization and X-ray diffraction analysis of Streptomyces coelicolor FGE.
• Biochemical assays to assess sulfatase activity in wild-type and FGE-deficient M. tuberculosis strains.

Main Results:

• A prokaryotic FGE from Mycobacterium tuberculosis was identified.
• The crystal structure of Streptomyces coelicolor FGE revealed significant similarity to human FGE, including catalytic cysteine residues.
• Biochemical and structural data suggest an oxidized cysteine modification in the active site.
• A mutant M. tuberculosis strain lacking FGE showed reduced global sulfatase activity.
• Residual sulfatase activity in the mutant indicates the presence of FGE-independent sulfatases.

Conclusions:

• Prokaryotes possess FGE homologs with structural and potentially functional similarities to their eukaryotic counterparts.
• The study provides insights into the conserved mechanism of sulfatase activation.
• The existence of FGE-independent sulfatases in M. tuberculosis warrants further investigation.