Microcin

Microcin is a type of bacteriocin, a proteinaceous or peptidic toxin produced by bacteria to inhibit the growth of similar or closely related bacterial strain(s). Microcins are produced by and active against Gram-negative bacteria. They are smaller than other bacteriocins, with a molecular weight less than 10 kDa.

Classification

Microcins are classified into two classes based on their molecular weight and post-translational modifications. Class I microcins are less than 5 kDa and undergo extensive post-translational modifications, while Class II microcins are 5-10 kDa and undergo limited post-translational modifications.

Mechanism of Action

Microcins exert their antibacterial activity by different mechanisms, including DNA gyrase inhibition, pore formation, and RNase activity. For instance, microcin B17 inhibits DNA gyrase, a type II topoisomerase, which is essential for DNA replication and transcription in bacteria.

Biosynthesis

The biosynthesis of microcins involves a nonribosomal peptide synthetase system. The genes responsible for the production, secretion, and immunity of microcins are usually organized in an operon.

Applications

Due to their potent antibacterial activity, microcins have potential applications in agriculture and medicine, particularly in the treatment of antibiotic-resistant bacterial infections.

See Also

• Bacteriocin
• Antibiotic resistance
• DNA gyrase
• Nonribosomal peptide