Fungal Cordycepin Biosynthesis Is Coupled with the Production of the Safeguard Molecule Pentostatin

Cordycepin (COR) and pentostatin (PTN) are adenosine analogs with related bioactivity profiles as both mimic adenosine and can inhibit some of the processes that are adenosine dependent. Both COR and PTN are also natural products and were originally isolated from the fungus Cordyceps militaris and the bacterium Streptomyces antibioticus, respectively. Here, we report that not only is PTN produced by C. militaris but that biosynthesis of COR is coupled with PTN production by a single gene cluster. We also demonstrate that this coupling is an important point of metabolic regulation where PTN safeguards COR from deamination by inhibiting adenosine deaminase (ADA) activity. ADA is not inhibited until COR reaches self-toxic levels, at which point ADA derepression occurs allowing for detoxification of COR to 3'-deoxyinosine. Finally, we show that using our biosynthetic insights, we can engineer C. militaris to produce higher levels of COR and PTN.