Chloramphenicol acetyltransferase

Chloramphenicol acetyltransferase (CAT) is an enzyme that detoxifies the antibiotic chloramphenicol and is responsible for chloramphenicol resistance in bacteria. This enzyme covalently attaches an acetyl group from acetyl-CoA to chloramphenicol, which prevents the drug from binding to ribosomes.

Structure

Chloramphenicol acetyltransferase is a relatively small protein, with a molecular weight of approximately 25,000 daltons. The enzyme is composed of two identical subunits, each of which binds one molecule of chloramphenicol and one molecule of acetyl-CoA. The active site of the enzyme is located in a cleft between the two subunits.

Function

The primary function of chloramphenicol acetyltransferase is to confer resistance to the antibiotic chloramphenicol. It does this by acetylating the hydroxyl group of chloramphenicol, which prevents the drug from binding to the bacterial ribosome and inhibiting protein synthesis. This modification effectively neutralizes the antibiotic and allows the bacteria to continue growing in its presence.

Clinical significance

Chloramphenicol acetyltransferase is a significant factor in the development of antibiotic resistance in bacteria. The gene encoding this enzyme is often found on plasmids, which can be easily transferred between bacteria. This allows for the rapid spread of chloramphenicol resistance in bacterial populations.

Research applications

In addition to its role in antibiotic resistance, chloramphenicol acetyltransferase has also been widely used as a reporter gene in molecular biology research. The enzyme's activity can be easily measured, making it a useful tool for studying gene expression and regulation.

See also

• Antibiotic resistance
• Chloramphenicol
• Acetyl-CoA
• Ribosome
• Plasmid