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| [[Image:2imw.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_2imw| PDB=2imw | SCENE= }} | | {{STRUCTURE_2imw| PDB=2imw | SCENE= }} |
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| '''Mechanism of Template-Independent Nucleotide Incorporation Catalyzed by a Template-Dependent DNA Polymerase'''
| | ===Mechanism of Template-Independent Nucleotide Incorporation Catalyzed by a Template-Dependent DNA Polymerase=== |
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| ==Overview==
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| Numerous template-dependent DNA polymerases are capable of catalyzing template-independent nucleotide additions onto blunt-end DNA. Such non-canonical activity has been hypothesized to increase the genomic hypermutability of retroviruses including human immunodeficiency viruses. Here, we employed pre-steady state kinetics and X-ray crystallography to establish a mechanism for blunt-end additions catalyzed by Sulfolobus solfataricus Dpo4. Our kinetic studies indicated that the first blunt-end dATP incorporation was 80-fold more efficient than the second, and among natural deoxynucleotides, dATP was the preferred substrate due to its stronger intrahelical base-stacking ability. Such base-stacking contributions are supported by the 41-fold higher ground-state binding affinity of a nucleotide analog, pyrene nucleoside 5'-triphosphate, which lacks hydrogen bonding ability but possesses four conjugated aromatic rings. A 2.05 A resolution structure of Dpo4*(blunt-end DNA)*ddATP revealed that the base and sugar of the incoming ddATP, respectively, stack against the 5'-base of the opposite strand and the 3'-base of the elongating strand. This unprecedented base-stacking pattern can be applied to subsequent blunt-end additions only if all incorporated dAMPs are extrahelical, leading to predominantly single non-templated dATP incorporation.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17095011}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17095011 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17095011}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Yang, W.]] | | [[Category: Yang, W.]] |
| [[Category: Blunt end dna y-family polymerase dna replication]] | | [[Category: Blunt end dna y-family polymerase dna replication]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 07:40:20 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 02:43:58 2008'' |
