Structural insights into yeast DNA polymerase delta by small angle X-ray scattering

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• DNA polymerase delta (Poldelta) is crucial for DNA replication in eukaryotes.
• The assembly and structural conformation of yeast Poldelta subunits (Pol3, Pol31, Pol32) remain incompletely understood.

Purpose of the Study:

• To elucidate the structural assembly and conformation of a three-subunit yeast Poldelta complex (Poldelta(T)) using small-angle X-ray scattering (SAXS).
• To propose a model for the orientation of accessory subunits (Pol31-Pol32N) relative to the catalytic core (Pol3).

Main Methods:

• Small-angle X-ray scattering (SAXS) analysis of the yeast Poldelta(T) complex.
• Computational modeling to interpret SAXS data and reconstruct the complex's envelope.

Main Results:

• SAXS analysis revealed Poldelta(T) adopts an elongated conformation with a radius of gyration (Rg) of ~52 Å and a maximal dimension of ~190 Å.
• A proposed orientation of the Pol31-Pol32N subunits relative to the Pol3 catalytic core was determined.
• Significant conformational flexibility was observed, suggesting adaptability at the replication fork.

Conclusions:

• The study provides structural insights into the yeast Poldelta complex assembly.
• The elongated and flexible structure of Poldelta(T) likely facilitates its function in DNA replication.
• Findings contribute to understanding the coordination of DNA polymerases with other replication machinery.