Glutathione transferase in bacteria: subunit composition and antigenic characterization

Area of Science:

• Biochemistry
• Microbiology
• Enzymology

Background:

• Glutathione transferase (GST) enzymes are crucial in detoxification pathways.
• Investigating GST presence and function in various bacterial species is important for understanding microbial defense mechanisms.

Purpose of the Study:

• To determine the presence and characteristics of glutathione transferase (GST) in a panel of clinically relevant bacterial strains.
• To investigate the antigenic properties of bacterial GSTs and their potential role in antibiotic resistance.

Main Methods:

• Glutathione (GSH)-affinity purification and SDS-PAGE were used to isolate and analyze bacterial GSTs.
• Western blot analysis with specific antiserum was employed to identify antigenically related GSTs.
• Minimum inhibitory concentrations (MICs) were determined for various antibiotics in the presence of bacterial GST.

Main Results:

• GST activity was detected in all tested bacterial strains, with purified enzymes forming dimers of approximately 22,500 Mr.
• A GST antigenically identical to Proteus mirabilis AF 2924 GST (Pm-GST-6.0) was identified in Enterobacter cloacae, Escherichia coli ATCC 25422, and Proteus vulgaris.
• The presence of Pm-GST-6.0, but not mammalian GST, elevated MIC values for several antibiotics in E. coli ATCC 25922.

Conclusions:

• Bacterial GSTs are present in diverse Gram-negative bacteria and share structural similarities.
• Bacterial GSTs, specifically Pm-GST-6.0, may contribute to antibiotic resistance by increasing resistance to multiple drug classes.
• Bacterial GSTs represent a potential defense mechanism against antibiotic effects in bacteria.