Resumen de Biosynthesis of 2′-Chloropentostatin and 2′-Amino-2′-Deoxyadenosine Highlights a Single Gene Cluster Responsible for Two Independent Pathways in Actinomadura sp. Strain ATCC 39365
Yaojie Gao, Gudan Xu, Pan Wu, Jing Liu, You-sheng Cai, Zixin Deng, Wenqing Chen
2′-Chloropentostatin (2′-Cl PTN, 2′-chloro-2′-deoxycoformycin) and 2′-amino-2′-deoxyadenosine (2′-amino dA) are two adenosine-derived nucleoside antibiotics coproduced by Actinomadura sp. strain ATCC 39365. 2′-Cl PTN is a potent adenosine deaminase (ADA) inhibitor featuring an intriguing 1,3-diazepine ring, as well as a chlorination at C-2′ of ribose, and 2′-amino dA is an adenosine analog showing bioactivity against RNA-type virus infection. However, the biosynthetic logic of them has remained poorly understood. Here, we report the identification of a single gene cluster (ada) essential for the biosynthesis of 2′-Cl PTN and 2′-amino dA. Further systematic genetic investigations suggest that 2′-Cl PTN and 2′-amino dA are biosynthesized by independent pathways. Moreover, we provide evidence that a predicted cation/H+ antiporter, AdaE, is involved in the chlorination step during 2′-Cl PTN biosynthesis. Notably, we demonstrate that 2′-amino dA biosynthesis is initiated by a Nudix hydrolase, AdaJ, catalyzing the hydrolysis of ATP. Finally, we reveal that the host ADA (designated ADA1), capable of converting adenosine/2′-amino dA to inosine/2′-amino dI, is not very sensitive to the powerful ADA inhibitor pentostatin. These findings provide a basis for the further rational pathway engineering of 2′-Cl PTN and 2′-amino dA production.
