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Converting a DNA damage checkpoint effector (UmuD2C) into a lesion bypass polymerase (UmuD'2C)
A E Ferentz1, G C Walker, G Wagner
1Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
The EMBO Journal
|August 3, 2001
Summary
The structure of UmuD'2, a key component of DNA polymerase V in Escherichia coli, differs in solution compared to its crystal form. This suggests RecA protein may be crucial for activating its DNA repair function.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- The SOS response in Escherichia coli involves the induction of the umuDC operon.
- This operon produces UmuD2C and UmuD'2C (DNA polymerase V), essential for DNA repair and mutagenesis.
- UmuD'2 is formed from UmuD via RecA-mediated self-cleavage.
Purpose of the Study:
- To determine the solution structure of the UmuD'2 homodimer.
- To investigate the structural differences between UmuD'2 and the inactive UmuD'-UmuD heterodimer.
- To understand the implications of structural variations on DNA repair mechanisms.
Main Methods:
- Solution structure determination of UmuD'2 (PDB ID 1I4V).
- Comparative structural analysis with existing crystal structures.
- Analysis of protein-protein interactions within UmuD'2 and UmuD'-UmuD.
Main Results:
- The solution structure of UmuD'2 significantly differs from its crystal structure in overall shape.
- Key active site residues (S60 and K97) are not oriented towards each other in the solution structure.
- Structural distinctions were observed between UmuD'2 and the inactive UmuD'-UmuD heterodimer.
Conclusions:
- RecA protein may be required to assemble the active site of UmuD'2 for self-cleavage.
- Structural differences between UmuD'2C and UmuD2C likely contribute to their distinct biological roles.
- These findings provide insights into the regulation of translesion synthesis and SOS mutagenesis.