DnaA protein binding to the plasmid origin region can substitute for primosome assembly during replication of pBR322

Related Experiment Video

Updated: May 5, 2026

Recombineering Homologous Recombination Constructs in Drosophila
14:23

Recombineering Homologous Recombination Constructs in Drosophila

Published on: July 13, 2013

18.5K

W Seufert, W Messer

    Cell
    |January 16, 1987
    PubMed

    Insights

    The DnaA protein binds to the pBR322 origin, stimulating DNA replication. This binding replaces the need for protein i, directing other essential proteins to form the pre-replisome.

    Area of Science:

    • Molecular Biology
    • Genetics
    • Biochemistry

    Background:

    • The plasmid pBR322 relies on specific protein interactions for replication initiation.
    • The DnaA protein and primosomal components are crucial for bacterial DNA replication.

    Purpose of the Study:

    • To investigate the role of DnaA protein binding in pBR322 replication.
    • To elucidate the mechanism by which DnaA influences primosome assembly and function.

    Main Methods:

    • In vitro replication assays using pBR322 and its derivatives.
    • Construction and analysis of pBR322 deletion mutants lacking primosome assembly sites.
    • Biochemical characterization of protein-DNA interactions and replication requirements.

    Main Results:

    • DnaA protein significantly stimulates pBR322 replication in vitro.
    • DnaA protein presence renders primosomal protein i non-essential for replication.
    • Replication of pBR322 deletion derivatives requires DnaA protein and its binding site, independent of protein i.
    • Essential replication proteins DnaB and DnaG remain necessary for DnaA-mediated replication.

    Conclusions:

    • DnaA protein binding to the pBR322 origin acts as a substitute for canonical primosome assembly.
    • DnaA directs the assembly of key replication proteins (DnaB, DnaC, DnaG) at the origin.
    • This process, termed DnaA-directed pre-replisome formation, is a novel mechanism for replication initiation.

    More Related Videos

    Determination of the Optimal Chromosomal Locations for a DNA Element in Escherichia coli Using a Novel Transposon-mediated Approach11:12

    Determination of the Optimal Chromosomal Locations for a DNA Element in Escherichia coli Using a Novel Transposon-mediated Approach

    Published on: September 11, 2017

    6.8K
    Identification of Functional Protein Regions Through Chimeric Protein Construction11:39

    Identification of Functional Protein Regions Through Chimeric Protein Construction

    Published on: January 8, 2019

    10.0K

    Related Concept Videos

    Genomic DNA in Prokaryotes00:46

    Genomic DNA in Prokaryotes

    The genome of most prokaryotic organisms consists of double-stranded DNA organized into one circular chromosome in a region of cytoplasm called the nucleoid. The chromosome is tightly wound, or supercoiled, for efficient storage. Prokaryotes also contain other circular pieces of DNA called plasmids. These plasmids are smaller than the chromosome and often carry genes that confer adaptive functions, such as antibiotic resistance.
    Genomic Diversity in Bacteria
    Although bacterial genomes are much...
    42.4K
    Replication in Prokaryotes02:35

    Replication in Prokaryotes

    Overview
    86.7K
    Bacterial Transformation01:33

    Bacterial Transformation

    In 1928, bacteriologist Frederick Griffith worked on a vaccine for pneumonia, which is caused by Streptococcus pneumoniae bacteria. Griffith studied two pneumonia strains in mice: one pathogenic and one non-pathogenic. Only the pathogenic strain killed host mice.
    Griffith made an unexpected discovery when he killed the pathogenic strain and mixed its remains with the live, non-pathogenic strain. Not only did the mixture kill host mice, but it also contained living pathogenic bacteria that...
    52.1K
    Homologous Recombination02:31

    Homologous Recombination

    The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
    58.8K
    Replication in Prokaryotes01:32

    Replication in Prokaryotes

    DNA replication has three main steps: initiation, elongation, and termination. Replication in prokaryotes begins when initiator proteins bind to the single origin of replication (ori) on the cell's circular chromosome. Replication then proceeds around the entire circle of the chromosome in each direction from the two replication forks, resulting in two DNA molecules.
    Many Proteins Work Together to Replicate the Chromosome
    Replication is coordinated and carried out by a host of specialized...
    20.5K
    Other Unique Bacteria01:18

    Other Unique Bacteria

    Magnetic bacteria exhibit a directed movement called magnetotaxis, driven by structures called magnetosomes. These magnetosomes consist of chains of magnetic particles made of either magnetite (Fe₃O₄) or greigite (Fe₃S₄) and are organized in a linear conformation by a protein scaffold within invaginations of the cell membrane. The bacteria align along the north–south magnetic field lines, much like a compass needle. They are typically microaerophilic or anaerobic...
    576