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PpnP is a broad-specificity pyrimidine/purine nucleoside phosphorylase catalyzing phosphorolysis of nucleosides to yield a free nucleobase plus alpha-D-ribose 1-phosphate, supporting purine and pyrimidine salvage.
"is explicitly described as a broad-specificity pyrimidine/purine nucleoside phosphorylase in bacterial purine salvage context"
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The phosphorolysis chemistry cleaves the nucleoside N-glycosidic bond using inorganic phosphate, generating a nucleobase and ribose 1-phosphate.
"that cleaves nucleosides with phosphate to yield a nucleobase and D-ribose-1-phosphate"
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PpnP has a broad substrate range across purine and pyrimidine nucleosides.
"inosine, uridine, adenosine, guanosine, cytidine, thymidine, and xanthosine"
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PpnP acts in purine/pyrimidine salvage downstream of nucleoside uptake, producing reusable bases plus ribose 1-phosphate.
"downstream of nucleoside uptake, producing bases and ribose-1-phosphate for reuse"
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In metabolic engineering, ppnP deletion increases nucleoside (guanosine) titres, evidencing its role as a catabolic sink for nucleosides.
"its deletion measurably increases nucleoside product titres in industrially relevant fermentation contexts"
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Pathway organization implies a cytoplasmic site of action, as nucleosides are imported by membrane transporters and PpnP products feed intracellular metabolism.
"because nucleosides are first imported by membrane transporters and PpnP products feed intracellular regulation/metabolism"
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The KT2440 enzyme (PP_4248 / Q88F51) has not been directly biochemically characterized; the functional assignment is a family/ortholog-supported inference.
"organism-specific claims below are framed as"
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No retrieved primary study directly characterizes the P. putida KT2440 enzyme.
"no primary study explicitly mentions"