Lysines in the lyase active site of DNA polymerase β destabilize nonspecific DNA binding, facilitating searching and DNA gap recognition
| Autor: | Samuel H. Wilson, Julie K. Horton, Michael J. Howard, Ming-Lang Zhao |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
DNA polymerase DNA repair DNA damage viruses Biochemistry Mice 03 medical and health sciences chemistry.chemical_compound Catalytic Domain Enzyme Stability Animals Humans Protein–DNA interaction Molecular Biology DNA Polymerase beta 030102 biochemistry & molecular biology DNA synthesis biology Chemistry DNA Cell Biology Base excision repair Lyase 030104 developmental biology Enzymology biology.protein DNA Damage Protein Binding |
| Zdroj: | J Biol Chem |
| ISSN: | 0021-9258 |
| Popis: | DNA polymerase (pol) β catalyzes two reactions at DNA gaps generated during base excision repair, gap-filling DNA synthesis and lyase-dependent 5´-end deoxyribose phosphate removal. The lyase domain of pol β has been proposed to function in DNA gap recognition and to facilitate DNA scanning during substrate search. However, the mechanisms and molecular interactions used by pol β for substrate search and recognition are not clear. To provide insight into this process, a comparison was made of the DNA binding affinities of WT pol β, pol λ, and pol μ, and several variants of pol β, for 1-nt-gap-containing and undamaged DNA. Surprisingly, this analysis revealed that mutation of three lysine residues in the lyase active site of pol β, 35, 68, and 72, to alanine (pol β KΔ3A) increased the binding affinity for nonspecific DNA ∼11-fold compared with that of the WT. WT pol μ, lacking homologous lysines, displayed nonspecific DNA binding behavior similar to that of pol β KΔ3A, in line with previous data demonstrating both enzymes were deficient in processive searching. In fluorescent microscopy experiments using mouse fibroblasts deficient in PARP-1, the ability of pol β KΔ3A to localize to sites of laser-induced DNA damage was strongly decreased compared with that of WT pol β. These data suggest that the three lysines in the lyase active site destabilize pol β when bound to DNA nonspecifically, promoting DNA scanning and providing binding specificity for gapped DNA. |
| Databáze: | OpenAIRE |
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