Structural Insights into Human p53R2, a p53-Inducible Ribonucleotide Reductase

Scientists have reported new findings on the X-ray crystal structure of human p53R2, a protein crucial for DNA repair and replication. The study, published in Biochemistry, reveals significant differences in structure between human p53R2 and its homolog, hRRM2. These differences are believed to play a regulatory role in iron assimilation and enzyme activity.

Key Takeaways:

• Human p53R2 (hp53R2) is a 351-residue p53-inducible ribonucleotide reductase (RNR) small subunit, sharing 80% sequence identity with hRRM2.
• hp53R2 has a unique function, supplying dNTPs for DNA repair in a p53-dependent fashion, distinct from the normal maintenance of the dNTP pool for DNA replication.
• The first X-ray crystal structure of hp53R2 was determined to 2.6 A, showing monomers A and B with mono-and binuclear iron occupancy, respectively.
• Structural differences between hp53R2 and hRRM2 were identified, highlighting possible regulatory roles in iron assimilation and radical transfer pathways between the two enzymes.
• The sequence-structure-function correlations between hp53R2 and hRRM2 were revealed for the first time.
• The study's findings will be used to identify biological function, regulation mechanisms, and potential inhibitors in RNR small subunits.

Statistics:

• hp53R2 shares 80% sequence identity with hRRM2.
• The X-ray crystal structure of hp53R2 was determined to 2.6 A.
• The study identified three regions with pronounced structural differences between hp53R2 and hRRM2.
• 351 residues make up the human p53R2 protein.

Sources:

• "2.6 A X-ray crystal structure of human p53R2, a p53-inducible ribonucleotide reductase." Biochemistry, 2009;48(46):11134-41.
• University of California, Department of Chemistry.