title: Enhancement of human DNA polymerase η activity and fidelity is dependent upon a bipartite interaction with the Werner syndrome protein.
abstract: We have investigated the interaction between human DNA polymerase η (hpol η) and the Werner syndrome protein (WRN). Functional assays revealed that the WRN exonuclease and RecQ C-terminal (RQC) domains are necessary for full stimulation of hpol η-catalyzed formation of correct base pairs. We find that WRN does not stimulate hpol η-catalyzed formation of mispairs. Moreover, the exonuclease activity of WRN prevents stable mispair formation by hpol η. These results are consistent with a proofreading activity for WRN during single-nucleotide additions. ATP hydrolysis by WRN appears to attenuate stimulation of hpol η. Pre-steady-state kinetic results show that k(pol) is increased 4-fold by WRN. Finally, pulldown assays reveal a bipartite physical interaction between hpol η and WRN that is mediated by the exonuclease and RQC domains. Taken together, these results are consistent with alteration of the rate-limiting step in polymerase catalysis by direct protein-protein interactions between WRN and hpol η. In summary, WRN improves the efficiency and fidelity of hpol η to promote more effective replication of DNA.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, USA.
authors.forename: Leena
authors.initials: L
authors.lastname: Maddukuri
authors.forename: Amit
authors.initials: A
authors.lastname: Ketkar
authors.forename: Sarah
authors.initials: S
authors.lastname: Eddy
authors.forename: Maroof K
authors.initials: MK
authors.lastname: Zafar
authors.forename: Wezley C
authors.initials: WC
authors.lastname: Griffin
authors.forename: Robert L
authors.initials: RL
authors.lastname: Eoff
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002384:Catalysis; D004247:DNA / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D004261:DNA Replication / Q000502:physiology*; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005090:Exodeoxyribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D053484:RecQ Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000071657:Werner Syndrome Helicase
chemical_list: D000255:Adenosine Triphosphate; D004247:DNA; D004259:DNA-Directed DNA Polymerase; C546205:POLN protein, human; D005090:Exodeoxyribonucleases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase