Bacterial glutathione transferase

Bacterial glutathione transferases (GSTs; EC 2.5.1.18) are part of a superfamily of enzymes that play a crucial role in cellular detoxification.

The considerable amount of protein sequence variation has led to the general belief that GSTs carry out a very wide variety of glutathione-dependent conjugation functions.

[4] Bacterial GSTs are involved in a variety of distinct processes such as biotransformation of toxic compounds, protection against several stresses, and antibacterial drug resistance.

In its reduced form, glutathione plays a key role in the regulation of reactive oxygen species (ROS) in the cell.

[3] Sulfur itself is able to exist in several different oxidation states; this redox flexibility combined with its strong nucleophilic properties allows glutathione to oxidize/readily pick up electrons from reactive oxygen species.

[4] Bacterial glutathione transferases are specific to aerobic bacteria and mainly function in the detoxification of exogenous compounds and the relief of oxidative stress.

The reactive oxygen species then donates one electron to a glutathione molecule, completing the oxidation-reduction reaction and rendering it unable to perform oxidative damage to the cell.

This glutathione system acts as the major reduction-oxidation buffer in aerobic bacterial cells, contributing to the overall reduced cellular environment of the cytosol.

[5] One of the primary roles of bacterial glutathione transferases is to reduce the toxic effects of xenobiotics from the cell using the phase II system of detoxification metabolism.

[3] GSTs are essential in this process because they catalyze the nucleophilic attack of glutathione on various electrophilic residues of xenobiotic substrates, thereby preventing their disruption of vital cellular proteins and nucleic acids.

The active GST complex catalyzes the -SH residue on glutathione to perform a nucleophilic attack on electrophilic carbon, sulfur, or nitrogen atoms of the xenobiotic substrate.