scholarly journals Role of Hoogsteen Edge Hydrogen Bonding at Template Purines in Nucleotide Incorporation by Human DNA Polymerase ι

2006 ◽  
Vol 26 (17) ◽  
pp. 6435-6441 ◽  
Author(s):  
Robert E. Johnson ◽  
Lajos Haracska ◽  
Louise Prakash ◽  
Satya Prakash
Keyword(s):  
Hydrogen Bonding ◽  
Dna Polymerase ◽  
Active Site ◽  
Dna Polymerases ◽  
Human Dna ◽  
Nucleotide Incorporation ◽  
Template Specificity ◽  
Hydrogen Bonding Potential ◽  
Dna Polymerase Ι

ABSTRACT Human DNA polymerase ι (Pol ι) differs from other DNA polymerases in that it exhibits a marked template specificity, being more efficient and accurate opposite template purines than opposite pyrimidines. The crystal structures of Pol ι with template A and incoming dTTP and with template G and incoming dCTP have revealed that in the Pol ι active site, the templating purine adopts a syn conformation and forms a Hoogsteen base pair with the incoming pyrimidine which remains in the anti conformation. By using 2-aminopurine and purine as the templating residues, which retain the normal N7 position but lack the N6 of an A or the O6 of a G, here we provide evidence that whereas hydrogen bonding at N6 is dispensable for the proficient incorporation of a T opposite template A, hydrogen bonding at O6 is a prerequisite for C incorporation opposite template G. To further analyze the contributions of O6 and N7 hydrogen bonding to DNA synthesis by Pol ι, we have examined its proficiency for replicating through the 6 O-methyl guanine and 8-oxoguanine lesions, which affect the O6 and N7 positions of template G, respectively. We conclude from these studies that for proficient T incorporation opposite template A, only the N7 hydrogen bonding is required, but for proficient C incorporation opposite template G, hydrogen bonding at both the N7 and O6 is an imperative. The dispensability of N6 hydrogen bonding for proficient T incorporation opposite template A has important biological implications, as that would endow Pol ι with the ability to replicate through lesions which impair the Watson-Crick hydrogen bonding potential at both the N1 and N6 positions of templating A.

scholarly journals Requirement of Watson-Crick Hydrogen Bonding for DNA Synthesis by Yeast DNA Polymerase η

2003 ◽  
Vol 23 (14) ◽  
pp. 5107-5112 ◽  
Author(s):  
M. Todd Washington ◽  
Sandra A. Helquist ◽  
Eric T. Kool ◽  
Louise Prakash ◽  
Satya Prakash
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Dna Synthesis ◽  
Dna Polymerase ◽  
Active Site ◽  
Dna Polymerases ◽  
Dna Lesions ◽  
Geometric Constraints ◽  
High Fidelity ◽  
Nucleotide Incorporation

ABSTRACT Classical high-fidelity DNA polymerases discriminate between the correct and incorrect nucleotides by using geometric constraints imposed by the tight fit of the active site with the incipient base pair. Consequently, Watson-Crick (W-C) hydrogen bonding between the bases is not required for the efficiency and accuracy of DNA synthesis by these polymerases. DNA polymerase η (Polη) is a low-fidelity enzyme able to replicate through DNA lesions. Using difluorotoluene, a nonpolar isosteric analog of thymine unable to form W-C hydrogen bonds with adenine, we found that the efficiency and accuracy of nucleotide incorporation by Polη are severely impaired. From these observations, we suggest that W-C hydrogen bonding is required for DNA synthesis by Polη; in this regard, Polη differs strikingly from classical high-fidelity DNA polymerases.

scholarly journals The Loop of the TPR1 Subdomain of Phi29 DNA Polymerase Plays a Pivotal Role in Primer-Terminus Stabilization at the Polymerization Active Site

Biomolecules ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 648
Author(s):  
del Prado ◽  
Santos ◽  
Lázaro ◽  
Salas ◽  
de Vega
Keyword(s):  
Dna Polymerase ◽  
Active Site ◽  
Structural Changes ◽  
Binding Capacity ◽  
Dna Polymerases ◽  
Crystallographic Structure ◽  
Genome Replication ◽  
Terminal Protein ◽  
Phi29 Dna Polymerase

Bacteriophage Phi29 DNA polymerase belongs to the protein-primed subgroup of family B DNA polymerases that use a terminal protein (TP) as a primer to initiate genome replication. The resolution of the crystallographic structure showed that it consists of an N-terminal domain with the exonuclease activity and a C-terminal polymerization domain. It also has two subdomains specific of the protein-primed DNA polymerases; the TP Regions 1 (TPR1) that interacts with TP and DNA, and 2 (TPR2), that couples both processivity and strand displacement to the enzyme. The superimposition of the structures of the apo polymerase and the polymerase in the polymerase/TP heterodimer shows that the structural changes are restricted almost to the TPR1 loop (residues 304–314). In order to study the role of this loop in binding the DNA and the TP, we changed the residues Arg306, Arg308, Phe309, Tyr310, and Lys311 into alanine, and also made the deletion mutant Δ6 lacking residues Arg306–Lys311. The results show a defective TP binding capacity in mutants R306A, F309A, Y310A, and Δ6. The additional impaired primer-terminus stabilization at the polymerization active site in mutants Y310A and Δ6 allows us to propose a role for the Phi29 DNA polymerase TPR1 loop in the proper positioning of the DNA and TP-priming 3’-OH termini at the preinsertion site of the polymerase to enable efficient initiation and further elongation steps during Phi29 TP-DNA replication.

scholarly journals Human DNA Polymerase ι Promotes Replication through a Ring-Closed Minor-Groove Adduct That Adopts a syn Conformation in DNA

2005 ◽  
Vol 25 (19) ◽  
pp. 8748-8754 ◽  
Author(s):  
William T. Wolfle ◽  
Robert E. Johnson ◽  
Irina G. Minko ◽  
R. Stephen Lloyd ◽  
Satya Prakash ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Dna Polymerases ◽  
Minor Groove ◽  
Dna Lesions ◽  
Unsaturated Aldehyde ◽  
Cyclic Form ◽  
Human Dna ◽  
A Minor ◽  
Dna Polymerase Ι

ABSTRACT Acrolein, an α,β-unsaturated aldehyde, is generated in vivo as the end product of lipid peroxidation and from oxidation of polyamines. The reaction of acrolein with the N 2 group of guanine in DNA leads to the formation of a cyclic adduct, γ-hydroxy-1,N 2-propano-2′-deoxyguanosine (γ-HOPdG). Previously, we have shown that proficient replication through the γ-HOPdG adduct can be mediated by the sequential action of human DNA polymerases (Pols) ι and κ, in which Polι incorporates either pyrimidine opposite γ-HOPdG, but Polκ extends only from the cytosine. Since γ-HOPdG can adopt either a ring-closed cyclic form or a ring-opened form in DNA, to better understand the mechanisms that Pols ι and κ employ to promote replication through this lesion, we have examined the ability of these polymerases to replicate through the structural analogs of γ-HOPdG that are permanently either ring closed or ring opened. Our studies with these model adducts show that whereas the ring-opened form of γ-HOPdG is not inhibitory to synthesis by human Pols η, ι, or κ, only Polι is able to incorporate nucleotides opposite the ring-closed form, which is known to adopt a syn conformation in DNA. From these studies, we infer that (i) Pols η, ι, and κ have the ability to proficiently replicate through minor-groove DNA lesions that do not perturb the Watson-Crick hydrogen bonding of the template base with the incoming nucleotide, and (ii) Polι can accommodate a minor-groove-adducted template purine which adopts a syn conformation in DNA and forms a Hoogsteen base pair with the incoming nucleotide.

scholarly journals An Incoming Nucleotide Imposes an anti to syn Conformational Change on the Templating Purine in the Human DNA Polymerase-ι Active Site

Structure ◽  
2006 ◽  
Vol 14 (4) ◽  
pp. 749-755 ◽  
Author(s):  
Deepak T. Nair ◽  
Robert E. Johnson ◽  
Louise Prakash ◽  
Satya Prakash ◽  
Aneel K. Aggarwal
Keyword(s):  
Conformational Change ◽  
Dna Polymerase ◽  
Active Site ◽  
Human Dna ◽  
Dna Polymerase Ι

scholarly journals Human DNA Polymerase ι Utilizes Different Nucleotide Incorporation Mechanisms Dependent upon the Template Base

2004 ◽  
Vol 24 (2) ◽  
pp. 936-943 ◽  
Author(s):  
M. Todd Washington ◽  
Robert E. Johnson ◽  
Louise Prakash ◽  
Satya Prakash
Keyword(s):  
Dna Polymerase ◽  
Base Pair ◽  
Translesion Dna Synthesis ◽  
Human Dna ◽  
Nucleotide Incorporation ◽  
Steady State Kinetic ◽  
Y Family ◽  
State Kinetic ◽  
Dna Polymerase Ι ◽  
Better Than

ABSTRACT Human DNA polymerase ι (Polι) is a member of the Y family of DNA polymerases involved in translesion DNA synthesis. Polι is highly unusual in that it possesses a high fidelity on template A, but has an unprecedented low fidelity on template T, preferring to misincorporate a G instead of an A. To understand the mechanisms of nucleotide incorporation opposite different template bases by Polι, we have carried out pre-steady-state kinetic analyses of nucleotide incorporation opposite templates A and T. These analyses have revealed that opposite template A, the correct nucleotide is preferred because it is bound tighter and is incorporated faster than the incorrect nucleotides. Opposite template T, however, the correct and incorrect nucleotides are incorporated at very similar rates, and interestingly, the greater efficiency of G misincorporation relative to A incorporation opposite T arises predominantly from the tighter binding of G. Based on these results, we propose that the incipient base pair is accommodated differently in the active site of Polι dependent upon the template base and that when T is the templating base, Polι accommodates the wobble base pair better than the Watson-Crick base pair.

scholarly journals Lesion orientation of O4-alkylthymidine influences replication by human DNA polymerase η

2016 ◽  
Vol 7 (8) ◽  
pp. 4896-4904 ◽  
Author(s):  
D. K. O'Flaherty ◽  
A. Patra ◽  
Y. Su ◽  
F. P. Guengerich ◽  
M. Egli ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Dna Polymerase ◽  
Active Site ◽  
Ternary Complexes ◽  
Human Dna

Conformation of the α-carbon of O4-alkylthymidine was shown to exert an influence on human DNA polymerase η (hPol η) bypass. Crystal structures of hPol η·DNA·dNTP ternary complexes reveal a unique conformation adopted by O4-methylthymidine, where the nucleobase resides nestled at the active site ceiling where hydrogen-bonding with the incoming nucleotide is prevented.

scholarly journals Localization of the Deoxyribose Phosphate Lyase Active Site in Human DNA Polymerase ι by Controlled Proteolysis

2003 ◽  
Vol 278 (32) ◽  
pp. 29649-29654 ◽  
Author(s):  
Rajendra Prasad ◽  
Katarzyna Bebenek ◽  
Esther Hou ◽  
David D. Shock ◽  
William A. Beard ◽  
...  
Keyword(s):  
Dna Polymerase ◽  
Active Site ◽  
Human Dna ◽  
Dna Polymerase Ι
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