Abstract:
:The remarkable fidelity of most DNA polymerases depends on a series of early steps in the reaction pathway which allow the selection of the correct nucleotide substrate, while excluding all incorrect ones, before the enzyme is committed to the chemical step of nucleotide incorporation. The conformational transitions that are involved in these early steps are detectable with a variety of fluorescence assays and include the fingers-closing transition that has been characterized in structural studies. Using DNA polymerase I (Klenow fragment) labeled with both donor and acceptor fluorophores, we have employed single-molecule fluorescence resonance energy transfer to study the polymerase conformational transitions that precede nucleotide addition. Our experiments clearly distinguish the open and closed conformations that predominate in Pol-DNA and Pol-DNA-dNTP complexes, respectively. By contrast, the unliganded polymerase shows a broad distribution of FRET values, indicating a high degree of conformational flexibility in the protein in the absence of its substrates; such flexibility was not anticipated on the basis of the available crystallographic structures. Real-time observation of conformational dynamics showed that most of the unliganded polymerase molecules sample the open and closed conformations in the millisecond timescale. Ternary complexes formed in the presence of mismatched dNTPs or complementary ribonucleotides show unique FRET species, which we suggest are relevant to kinetic checkpoints that discriminate against these incorrect substrates.
journal_name
Proc Natl Acad Sci U S Aauthors
Santoso Y,Joyce CM,Potapova O,Le Reste L,Hohlbein J,Torella JP,Grindley ND,Kapanidis ANdoi
10.1073/pnas.0910909107subject
Has Abstractpub_date
2010-01-12 00:00:00pages
715-20issue
2eissn
0027-8424issn
1091-6490pii
0910909107journal_volume
107pub_type
杂志文章abstract::Hydrocortisone at physiological concentrations reversibly inhibits DNA synthesis in ST1 cells (a line of mouse fibroblasts possessing 40 chromosomes and derived from Swiss 3T3 cells). This inhibitory activity is a property of glucocorticoids, but the beta-OH of C-11 of glucocorticoids is not essential for the inhibiti...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1978-06-01 00:00:00
abstract::We have previously identified and purified a cell surface glycoprotein from retina and brain, called neural cell adhesion molecule or N-CAM, that appears to be involved in neural cell--cell adhesion, the fasciculation of neurites, and the formation of normal tissue patterns in the retina. The present studies reveal th...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:1982-01-01 00:00:00
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doi:10.1073/pnas.0901870106
更新日期:2009-08-25 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
doi:10.1073/pnas.71.10.4002
更新日期:1974-10-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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pub_type: 历史文章,杂志文章
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1992-11-15 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1993-04-15 00:00:00
abstract::Treatment of C57BL/6 or NOD mice with a monoclonal antibody to the CSF-1 receptor resulted in depletion of the resident macrophages of pancreatic islets of Langerhans that lasted for several weeks. Depletion of macrophages in C57BL/6 mice did not affect multiple parameters of islet function, including glucose response...
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abstract::A new common cell-surface antigen associated with murine and feline C-type RNA leukemia viruses was demonstrated by the use of rabbit antiserum against feline leukemia virus and the indirect membrane immunofluorescence test. Common cell-surface antigen was found in all leukemias of all strains of mice tested, in norma...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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更新日期:1973-06-01 00:00:00
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
pub_type: 杂志文章
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journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:1985-04-01 00:00:00
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abstract::Current issues pertaining to theoretical simulations of materials, with a focus on systems of nanometer-scale dimensions, are discussed. The use of atomistic simulations as high-resolution numerical experiments, enabling and guiding formulation and testing of analytic theoretical descriptions, is demonstrated through ...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2005-05-10 00:00:00
abstract::Sustained activity of mammalian methionine synthase (MS) requires MS reductase (MSR), but there have been few studies of the interactions between these two proteins. In this study, recombinant human MS (hMS) and MSR (hMSR) were expressed in baculovirus-infected insect cells and purified to homogeneity. hMSR maintained...
journal_title:Proceedings of the National Academy of Sciences of the United States of America
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更新日期:2006-06-20 00:00:00