Human de novo purine biosynthesis.

Area of Science:

• Biochemistry
• Cell Biology
• Metabolic Regulation

Background:

• The human de novo purine biosynthetic pathway synthesizes essential purine nucleotides.
• Evidence suggested pathway enzymes may form multi-enzyme complexes (metabolons).
• Purinosomes, discrete puncta of pathway enzymes, were previously identified.

Purpose of the Study:

• To review the human de novo purine biosynthetic pathway.
• To elaborate on purinosome assembly, function, and regulation.
• To discuss the implications for metabolic pathway organization.

Main Methods:

• Literature review of the de novo purine biosynthetic pathway.
• Analysis of studies on fluorescently-tagged enzyme chimeras forming purinosomes.
• Examination of evidence for purinosome assembly, ancillary protein roles, and cellular localization.
• Review of data on purinosome function in intermediate channeling and protein condensate formation.

Main Results:

• Pathway enzymes catalyze specific reactions with defined physical properties.
• Purinosomes assemble at the microtubule/mitochondria interface.
• At endogenous levels, purinosomes channel intermediates from phosphoribosyl pyrophosphate to AMP and GMP.
• Purinosomes function as protein condensates, with potential roles for ancillary proteins.

Conclusions:

• Purinosomes represent the de novo purine biosynthetic metabolon.
• Signaling pathways, potentially involving kinases due to enzyme phosphorylation, regulate purinosome assembly/disassembly.
• Findings offer insights into how metabolic pathways are organized for function.