A cyanobacterial adenine prenyltransferase enables longer-chain N6 prenylation

Adenine is a ubiquitous nucleobase found in nucleic acids, cofactors, and signaling molecules and mediates diverse molecular interactions. Here, we identify TvAPT, an adenine prenyltransferase from the cyanobacterium Trichormus variabilis NIES-23. Unlike canonical enzymes limited to C5 dimethylallylation, TvAPT efficiently catalyzes the unprecedented N6-prenylation of adenine-containing substrates using extended prenyl donors (C10 and C15), markedly increasing the hydrophobicity of the adenine moiety. X-ray structural analysis and protein engineering revealed that an enlarged prenyl-binding pocket enables this donor promiscuity, allowing rational tuning of prenyl-donor preference. These findings establish TvAPT as a versatile biocatalytic platform that expands the chemical space of adenine-containing molecules for biomolecular engineering, as demonstrated by the synthesis of membrane-permeable nucleotides and analogues of plant signaling molecules.