Indole N-Linked Hydroperoxyl Adduct of Protein-Derived Cofactor Modulating Catalase-Peroxidase Functions

Area of Science:

• Biochemistry
• Enzymology
• Microbiology

Background:

• Bifunctional catalase-peroxidase (KatG) is essential for pathogens like Mycobacterium tuberculosis to neutralize hydrogen peroxide during infection.
• KatG utilizes a unique methionine-tyrosine-tryptophan (MYW) crosslinked cofactor for its catalytic functions.

Purpose of the Study:

• To investigate the chemical stability and functional implications of the indole nitrogen-linked hydroperoxyl adduct (MYW-OOH) in Mycobacterium tuberculosis KatG.
• To determine if MYW-OOH occurs naturally and understand its role in KatG's enzymatic activity.

Main Methods:

• Isolation of Mycobacterium tuberculosis KatG predominantly containing the MYW-OOH adduct.
• Chemical stability and functional assays of MYW-OOH-containing KatG under varying conditions (peroxide exposure, temperature).

Main Results:

• Discovery of the naturally occurring indole nitrogen-linked hydroperoxyl adduct (MYW-OOH) in solution-state Mycobacterium tuberculosis KatG.
• MYW-OOH was found to inhibit KatG's catalase activity, acting as a temporary "lock".
• The hydroperoxyl adduct is releasable upon exposure to peroxide or increased temperature, restoring enzyme function.

Conclusions:

• The MYW-OOH form represents a dormant yet primed state of KatG.
• Releasable N-linked hydroperoxyl modifications play a significant role in KatG enzymatic function.
• Findings offer insights into chemical strategies targeting KatG in pathogenic bacteria.