Characterization of a multicopper oxidase gene from Staphylococcus aureus

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• Staphylococcus aureus is a significant human pathogen.
• Multicopper oxidases are enzymes involved in various biological processes.
• The specific role of multicopper oxidases in S. aureus was not well understood.

Purpose of the Study:

• To clone and characterize a multicopper oxidase gene (mco) from Staphylococcus aureus.
• To investigate the enzymatic activity of the recombinant multicopper oxidase.
• To determine the physiological roles of mco in S. aureus, particularly concerning copper homeostasis and oxidative stress.

Main Methods:

• Gene cloning and overexpression of the multicopper oxidase from S. aureus.
• Purification of the recombinant enzyme.
• Enzymatic assays using 3,3'-dimethoxybenzidine as a substrate in the presence of copper.
• Gene disruption (mco knockout) in S. aureus.
• Phenotypic analysis of the knockout mutant for copper sensitivity and hydrogen peroxide resistance.
• Northern blot analysis to assess mco gene transcription.

Main Results:

• The recombinant multicopper oxidase was successfully purified and demonstrated enzymatic activity, oxidizing 3,3'-dimethoxybenzidine with copper.
• Disruption of the mco gene resulted in increased sensitivity to copper and enhanced resistance to hydrogen peroxide.
• Northern blot analysis revealed that mco transcription is induced by copper.

Conclusions:

• The cloned multicopper oxidase from Staphylococcus aureus is a functional enzyme.
• The mco gene plays a crucial role in maintaining copper homeostasis and responding to oxidative stress in S. aureus.
• Copper is a key regulator of mco gene expression.