Identification of the minimal bacterial 2'-deoxy-7-amido-7-deazaguanine synthesis machinery.

The 7-deazapurine derivatives, 2'-deoxy-7-cyano-7-deazaguanosine (dPreQ ) and 2'-deoxy-7-amido-7-deazaguanosine (dADG) are recently discovered DNA modifications encoded by the dpd cluster found in a diverse set of bacteria. Here we identify the genes required for the formation of dPreQ and dADG in DNA and propose a biosynthetic pathway. The preQ base is a precursor that in Salmonella Montevideo, is synthesized as an intermediate in the pathway of the tRNA modification queuosine.