FIGURE 5.

Purine precursors are depleted during SasA expression. (A) Heat map of metabolite changes in cells after sasA or sasA^D87G expression. Red box highlights the changes in the level of PRPP-IMP pathway metabolites in addition to adenylosuccinate (S-AMP) and xanthosine monophosphate (XMP). PRPP, Phosphoribosyl pyrophosphate; FGAR, Phosphoribosyl-N-formylglycineamide; SAICAR, Phosphoribosylaminoimidazolesuccinocarboxamide; AICAR, 5-Aminoimidazole-4-carboxamide ribonucleotide; FAICAR, 5-Formamidoimidazole-4-carboxamide ribotide; IMP, Inosine monophosphate. Numbers indicate mean fold-change in binary logarithm relative to untreated cells. (B) Summary of metabolite changes in the de novo purine biosynthesis pathway in SasA-expressing cells. Bar plots shown are levels of SAICAR, AICAR, FAICAR, IMP, S-AMP, and XMP before and after sasA or sasA^D87G expression. PurB, Adenylsuccinate lyase; PurH, Phosphoribosylaminoimidazole carboxamide formyltransferaseand inosine-monophosphate cyclohydrolase; GuaC, GMP reductase; HprT, Hypoxanthine phosphoribosyltransferase; PurA, Adenylosuccinate synthetase; GuaB, IMP dehydrogenase. UT: untreated, Induced: after induction. Data shown are LC-MS ion counts normalized to OD₆₀₀. Error bars indicate SD. n = 2. **p < 0.01, *p < 0.05, ns: not significant (Student’s t-test). Color-shaded are metabolites with log₂ fold-change > 2 as shown in (A). Solid and dashed red arrows indicate known and speculated inhibition by (p)ppGpp respectively.