Related Experiment Video

Updated: Aug 8, 2026

Kinetics of Lagging-strand DNA Synthesis In Vitro by the Bacteriophage T7 Replication Proteins
08:14

Kinetics of Lagging-strand DNA Synthesis In Vitro by the Bacteriophage T7 Replication Proteins

Published on: February 25, 2017

Virus- and cell-encoded tyrosine protein kinases inactivate DNA topoisomerases in vitro

Y C Tse-Dinh, T W Wong, A R Goldberg

    Nature
    |December 20, 1984
    PubMed

    Insights

    Tyrosine protein kinases, like pp60src, were found to inhibit DNA topoisomerase activity. This suggests a novel regulatory mechanism for DNA processing and cell growth control.

    Area of Science:

    • Biochemistry
    • Molecular Biology
    • Enzymology

    Background:

    • Tyrosine protein kinases are linked to cell growth signaling pathways.
    • DNA topoisomerases regulate DNA topology, affecting replication and transcription.
    • Topoisomerases can form covalent DNA-protein complexes via phosphotyrosine linkages.

    Purpose of the Study:

    • To investigate if tyrosine protein kinases modulate DNA topoisomerase activity.
    • To determine if phosphorylation of the DNA-binding tyrosine residue affects topoisomerase function.

    Main Methods:

    • Incubation of bacterial and calf thymus type I DNA topoisomerases.
    • Enzymatic assays using purified tyrosine protein kinases (pp60src and TPK75).

    Main Results:

    • A 10-fold loss of DNA topoisomerase activity was observed upon incubation with pp60src and TPK75.
    • This indicates that tyrosine protein kinases can negatively regulate topoisomerase function.

    Conclusions:

    • Tyrosine protein kinases may play a role in controlling DNA topoisomerase activity.
    • This interaction could represent a novel mechanism linking growth factor signaling to DNA metabolism.

    More Related Videos

    Purification of Viral DNA for the Identification of Associated Viral and Cellular Proteins08:26

    Purification of Viral DNA for the Identification of Associated Viral and Cellular Proteins

    Published on: August 31, 2017

    Simple and Fast Rolling Circle Amplification-Based Detection of Topoisomerase 1 Activity in Crude Biological Samples10:13

    Simple and Fast Rolling Circle Amplification-Based Detection of Topoisomerase 1 Activity in Crude Biological Samples

    Published on: December 2, 2022

    Related Concept Videos

    DNA Topoisomerases02:02

    DNA Topoisomerases

    Topoisomerases are enzymes that relax overwound DNA molecules during various cell processes, including DNA replication and transcription. These enzymes regulate positive and negative DNA supercoiling without changing the nucleotide sequence. DNA overwinding in a clockwise direction results in positively supercoiled DNA, whereas underwinding in a counterclockwise direction produces negatively supercoiled DNA.
    Types and Mechanism of action
    Topoisomerases are divided into two main types.  Type I...
    DNA Damage can Stall the Cell Cycle02:36

    DNA Damage can Stall the Cell Cycle

    In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
    DNA Damage Can Stall the Cell Cycle02:36

    DNA Damage Can Stall the Cell Cycle

    In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
    Inhibitors of Bacterial DNA Synthesis01:28

    Inhibitors of Bacterial DNA Synthesis

    Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These antibiotics are selectively...
    Inhibitors of Viral Protein Synthesis01:30

    Inhibitors of Viral Protein Synthesis

    Protein synthesis is indispensable for viral replication, as viruses lack the cellular machinery required for this process and must hijack the host's translational apparatus. In response, host cells deploy a critical innate immune defense involving interferons, specialized cytokines that play a central role in inhibiting viral propagation.Upon viral detection, infected cells release interferons that bind to receptors on adjacent uninfected cells, activating the JAK-STAT signaling pathway and...
    Antiviral Nucleoside Inhibitors01:22

    Antiviral Nucleoside Inhibitors

    Antiviral Nucleoside InhibitorsAntiviral nucleoside inhibitors are structural analogs of natural nucleosides that interfere with viral DNA or RNA synthesis. These compounds selectively target viral polymerases due to their resemblance to host nucleosides, thereby disrupting viral genome replication.Mechanism of Acyclovir ActionAcyclovir is a guanosine analog with a three-carbon acyclic side chain. It selectively targets herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2),...