Nourseothricin

Nourseothricin is a streptothricin antibiotic that is produced by Streptomyces noursei. It is a broad-spectrum antibiotic that is effective against both Gram-positive and Gram-negative bacteria, as well as fungi. Nourseothricin is commonly used in molecular biology as a selection marker for transformed cells.

Structure

Nourseothricin is a complex of three components: Nourseothricin A1, A2, and A3. Each component is a streptothricin antibiotic that consists of a guanidino moiety, a streptolidine moiety, and a sugar moiety. The three components differ in the sugar moiety: A1 has L-streptose, A2 has D-streptose, and A3 has D-streptamine.

Mechanism of action

Nourseothricin inhibits protein synthesis by binding to the ribosome and causing misreading of the genetic code. This leads to the production of nonfunctional proteins, which ultimately results in cell death.

Uses

In molecular biology, nourseothricin is used as a selection marker for transformed cells. Cells that have been successfully transformed with a plasmid containing a nourseothricin resistance gene can survive in the presence of the antibiotic, while non-transformed cells are killed.

Resistance

Resistance to nourseothricin is conferred by the sat1 gene, which encodes a nourseothricin acetyltransferase. This enzyme inactivates the antibiotic by acetylation.

See also

• Streptothricin
• Streptomyces noursei
• Antibiotic resistance

Nourseothricin Resources
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