ATP Binding to the Escherichia coli Clamp Loader Powers
Dec 09, 2011 · In summary, a simple assay for measuring β-clamp opening and closing was developed. Using this assay along with a clamp binding assay, the first evidence that E. coli clamp loaders may actively pry clamps open to load clamps onto DNA was obtained. The combination of real-time clamp binding and opening assays will serve as excellent tools for future experiments …
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The Role of Replication Clamp-Loader Protein HolC of
In Escherichia coli, DNA replication is catalyzed by an assembly of proteins, the DNA polymerase III holoenzyme.This complex includes the polymerase and proofreading subunits, the processivity clamp, and clamp loader complex. The holC gene encodes an accessory protein (known as χ) to the core clamp loader complex and is the only protein of the holoenzyme that binds to single …
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The Escherichia coli clamp loader can actively pry open
Mar 10, 2010 · Multi-protein clamp loader complexes are required to load sliding clamps onto DNA. In Escherichia coli the clamp loader contains three DnaX (τ/γ) proteins, δ, and δ′, which together form an asymmetric pentameric ring that also interacts with ψχ. Here we used mass spectrometry to examine the assembly and dynamics of the clamp loader complex.
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The Role of Replication Clamp-Loader Protein HolC of
In Escherichia coli, DNA replication is catalyzed by an assembly of proteins, the DNA polymerase III holoenzyme.This complex includes the polymerase and proofreading subunits, the processivity clamp, and clamp loader complex. The holC gene encodes an accessory protein (known as χ) to the core clamp loader complex and is the only protein of the holoenzyme that binds to single …
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A Single Subunit Directs the Assembly of the Escherichia
Mar 10, 2010 · Multi-protein clamp loader complexes are required to load sliding clamps onto DNA. In Escherichia coli the clamp loader contains three DnaX (τ/γ) proteins, δ, and δ′, which together form an asymmetric pentameric ring that also interacts with ψχ. Here we used mass spectrometry to examine the assembly and dynamics of the clamp loader complex.
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The Escherichia coli clamp loader can actively pry open
Oct 04, 2011 · Data in Figs. 5 and and6 6 show that clamp binding is faster than clamp opening, demonstrating that the E. coli clamp loader actively opens the β-clamp after binding as illustrated in the upper reaction pathway rather than passively capturing clamps …
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Escherichia coli mismatch repair protein - ScienceDirect
In Escherichia coli, the replisome consists of the DNA polymerase III holoenzyme, including DNA polymerase, proofreading exonuclease, processivity clamp and clamp loader, as well as a fork helicase, DnaB and primase, DnaG. We provide evidence here that one component of the clamp loader complex, HolC (or χ) plays a dual role via its ability to
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Three-dimensional structure of the β subunit of E. coli
May 01, 1992 · The crystal structure of the β subunit (processivity factor) of DNA polymerase III holoenzyme has been determined at 2.5 Å resolution. A dimer of the β subunit (M r = 2 × 40.6 kd, 2 × 366 amino acid residues) forms a ring-shaped structure lined by 12 α helices that can encircle duplex DNA. The structure is highly symmetrical, with each monomer containing three domains …
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Alternative complexes formed by the Escherichia coli …
A simple fluorescence-based clamp opening assay was developed to address this question and to determine how ATP binding contributes to clamp opening. A direct comparison of real time binding and opening reactions revealed that the Escherichia coli γ complex binds β first and then opens the clamp. Mutation of conserved "arginine fingers" in
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Conserved residues in the delta subunit help the E. coli
The Escherichia coli clamp loader, gamma complex (gamma(3)deltadelta'lambdapsi), catalyzes ATP-driven assembly of beta clamps onto primer-template DNA (p/tDNA), enabling processive replication. The mechanism by which gamma complex targets p/tDNA for clamp assembly is not resolved. According to previous studies, charged/polar amino acids inside
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Mechanism of Sliding Clamp Loading by the Escherichia coli
The role of the DnaX clamp loader is to sliding clamp on DNA. E. coli DnaX clamp loader complex is composed of (38, 99, 159) In E. coli the gene dnaX dnaX is a truncated form of the full gene product (47 kDa) (55) frameshift that occurs during translation and causes the ribosome to shift the reading frame by 1 which results in the ribosome
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The δ Subunit of DNA Polymerase III Holoenzyme Serves as a
In Escherichia coli, the circular β sliding clamp facilitates processive DNA replication by tethering the polymerase to primer-template DNA. When synthesis is complete, polymerase dissociates from β and DNA and cycles to a new start site, a primed template loaded with β. DNA polymerase cycles frequently during lagging strand replication while synthesizing 1–2-kilobase Okazaki …
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Independent Positioning and Action of Escherichia coli
Fluorescent Replisome Foci Mark Replication Forks. Fluorescent C-terminal fusion-protein derivatives of E. coli replisome components, expressed from their endogenous chromosomal promoters, were constructed and their phenotypes assessed by growth, flow cytometry, and microscopy. Fusions containing components of the PolIII holoenzyme, the clamp loader, and …
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The Escherichia coli Clamp Loader Can Actively Pry Open
In E. coli, the clamp loader and (I clamp are utilized in DNA replication from initiation at the origin to DNA partitioning of parent and daughter chromosomes upon termination (Katayama, 2001; Levine and Marians, 1998).
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Three-dimensional structure of the β subunit of E. coli
May 01, 1992 · The crystal structure of the β subunit (processivity factor) of DNA polymerase III holoenzyme has been determined at 2.5 Å resolution. A dimer of the β subunit (M r = 2 × 40.6 kd, 2 × 366 amino acid residues) forms a ring-shaped structure lined by 12 α helices that can encircle duplex DNA. The structure is highly symmetrical, with each monomer containing three domains …
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Mapping the interaction of DNA with the Escherichia coli
clamp was replaced by the dimeric E. coli β clamp3. RNA-DNA hetero-duplex was positioned into the interior of the clamp loader spiral, with clamp loader subunits tracking along its minor groove. In bacteria, RNA primers are laid down by the primase enzyme, although clamp loaders can load clamps onto either RNA-DNA or DNA-DNA primer-templates
Get a quoteMechanism of Loading the Escherichia coli DNA Polymerase
The Escherichia coli DNA polymerase III γ complex clamp loader assembles the ring-shaped β sliding clamp onto DNA. The core polymerase is tethered to the template by β, enabling processive replication of the genome. Here we investigate the DNA substrate specificity of the clamp-loading reaction by measuring the pre-steady-state kinetics of DNA binding and ATP …
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Molecular Machines of the Cell Replisome mechanics
Evidence as to how replicases employ clamps and clamp loaders to carry out concurrent leading and lagging strand synthesis efficiently is mainly derived from biochemical and structural studies of E. coli and bacteriophage T4 replication systems (reviewed in Refs [2,20]). Because our current structural understanding of the E. coli replica-
Get a quoteThe Escherichia coli Clamp Loader Can - ScienceDirect
Sep 18, 1998 · The E. coli clamp loader uses ATP to convert the inefficient polymerase III core enzyme into a highly processive DNA replicating machine. Earlier studies have demonstrated that γ complex loads the circular clamp β onto a primed DNA template, and β tethers the polymerase to DNA, facilitating highly processive DNA synthesis.
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DNA polymerase clamp loaders and DNA recognition - Bowman
Nov 26, 2004 · Clamp loader structure. Three representations of the E. coli clamp loader (γ complex – panels A, C, and E) and the S. cerevisiae clamp loader (replication factor C, RFC – panels B, D, and F). The five subunits of each clamp loader complex are denoted by the letters A–E, with analogous subunits indicated by matching colors.
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