Figure 1

Metabolic map of the purine biosynthetic pathway. Dashed lines indicate multiple enzymatic steps; boxes denote contributing enzymes of de novo biosynthetic pathway (dark gray) and salvage pathway (light gray). Red lines indicate feedback inhibition of the rate controlling step of the purine biosynthetic pathway, regulating the activity of the PRPP amidotransferase by the most stringent inhibitors GMP and AMP based on Zhou et al. [38]. Abbreviations: R5P, ribose 5-phosphate; PRPP, 5-phosphoribosyl 1-pyrophosphate; IMP, inosine 5-monophosphate; AMP, adenosine 5-monophosphate; XMP xanthosine 5-monophosphate; GMP, guanosine 5-monophosphate; purA, adenylosuccinate synthetase; purB, adenylosuccinate lyase; guaB2, IMP dehydrogenase; guaA, GMP synthase; apt , adenine phosphoribosyltransferase; hpt, hypoxanthine-guanine phosphoribosyltransferase.