Tetracycline

Mode of Action

Tetracyclines (there are many) enter the cell by diffusion through OmpF porins. It inhibits growth by preventing codon-anticodon interactions during translation.

Resistance Mechanism

There are a number of resistance mechanisms, most require tetracycline antiporters. The most commonly used is the tetA(C) gene. The gene product of tetA(C) forms a pore in the inner membrane and exports one tet molecule for every proton imported. Molecular Cloning states that tet resistance has a number of adverse affects on the cell, chief among those being a reduction in growth rate and viability.

Dosage

• Using a plasmid with copy number 15-20, 20μg/ml tet has proved a successful selector. The reduction in growth rate, described above was significant.
• The RajBhandary lab uses 5μg/ml and see a minimal reduction in growth rate and never lose plasmid from their cells.

Properties

• Molecular Weight - 480.9g

References

• Molecular Cloning
• Wikipedia Tetracycline page