Cells have two purine pathways that synthesize adenine and guanine ribonucleotides from phosphoribose via inosylate. A chemical hybrid between adenine and guanine, 2-aminoadenine (Z), replaces adenine in the DNA of the cyanobacterial virus S-2L. We show that S-2L and Vibrio phage PhiVC8 encode a third purine pathway catalyzed by PurZ, a distant paralog of succinoadenylate synthase (PurA), the enzyme condensing aspartate and inosylate in the adenine pathway ...
Cells have two purine pathways that synthesize adenine and guanine ribonucleotides from phosphoribose via inosylate. A chemical hybrid between adenine and guanine, 2-aminoadenine (Z), replaces adenine in the DNA of the cyanobacterial virus S-2L. We show that S-2L and Vibrio phage PhiVC8 encode a third purine pathway catalyzed by PurZ, a distant paralog of succinoadenylate synthase (PurA), the enzyme condensing aspartate and inosylate in the adenine pathway. PurZ condenses aspartate with deoxyguanylate into dSMP (N6-succino-2-amino-2'-deoxyadenylate), which undergoes defumarylation and phosphorylation to give dZTP (2-amino-2'-deoxyadenosine-5'-triphosphate), a substrate for the phage DNA polymerase. Crystallography and phylogenetics analyses indicate a close relationship between phage PurZ and archaeal PurA enzymes. Our work elucidates the biocatalytic innovation that remodeled a DNA building block beyond canonical molecular biology.
Organizational Affiliation:
Biology of Gram-Positive Pathogens, Institut Pasteur, CNRS-UMR 2001, Paris, France. pierre-alexandre.kaminski@pasteur.fr.
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