Question

Why does cordycepin end transcription?

Answer 1

Cordycepin is a purine nucleoside antimetabolite and antibiotic isolated from the fungus Cordycepin militaris.

Explanation:

Cordycepin is an adenosine analogue, which is readily phosphorylated to its mono, di and triphosphate form intracellularly. Triphosphate Cordycepin can be incorporated into RNA and inhibits transcription elongation and RNA synthesis due to the absence of hydroxyl moiety at the 3' position.

Just as cordycepin is very similar to adenosine, some enzymes cannot discriminate between the two. Therefore it can participate in certain biochemical reactions. For example, it can be incorporated into an RNA molecule, thus causing the premature termination of its synthesis. At high doses cordycepin indirectly reduces protein synthesis to very low levels. It shuts down a signal transduction pathway - mTOR pathway, which controls protein synthesis.

Cordycepin has displayed cytotoxicity against some leukaemia cell lines, in vitro. Cordycepin has also been reported to have numerous biological activities including the inhibition of cell proliferation, induction of apoptosis, inhibition of platelet aggregation, inhibition of cell migration and invasivness and inhibition of inflammation.