Gene copy number, resistance mechanisms

Multicopy plasmids offer a limited, but still instructive comparison. Plasmids are replicating clusters of genes in bacteria. Under certain conditions they confer beneficial traits (such as resistance against antibiotics) on the bacterial host. They can also be passed on by conjugation between cells. A well elucidated mechanism of copy number control of abundant plasmids relies on a frans-acting inhibitor and czs-acting activator. For example, the ColE 1 plasmid in Escherichia coli blocks the action of the RNA primer (activator) by... 

The mechanism of action of both artemisinin and related compounds has been linked to inhibition of the parasite-encoded sarco-endoplasmic reticulum Ca -ATPase (SERCA) PfATP6, which was supported by decreased resistance in organisms with lower copy numbers of the gene " and of polymorphism in the genes in the field. Further work into the mechanism of action of artemisinin is ongoing in many laboratories around the world and there is evidence for involvement with chelation of nonheme iron by most if not all of the tri-oxo-containing compounds, be they modified natural products or synthetics. ... 

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