Related Experiment Video

Updated: Mar 29, 2026

Reliable Mechanochemistry: Protocols for Reproducible Outcomes of Neat and Liquid Assisted Ball-mill Grinding Experiments
13:05

Reliable Mechanochemistry: Protocols for Reproducible Outcomes of Neat and Liquid Assisted Ball-mill Grinding Experiments

Published on: January 23, 2018

11.3K

Directed and persistent movement arises from mechanochemistry of the ParA/ParB system

Longhua Hu1, Anthony G Vecchiarelli2, Kiyoshi Mizuuchi2

  • 1Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892;

Proceedings of the National Academy of Sciences of the United States of America
|December 10, 2015
PubMed

Insights

The bacterial ParA/ParB system drives DNA segregation using a diffusion ratchet mechanism. This process relies on transient protein tethers, enabling directed plasmid movement without traditional motor proteins.

Area of Science:

  • Molecular Biology
  • Microbiology
  • Biophysics

Background:

  • Faithful genetic inheritance relies on precise DNA segregation before cell division.
  • Bacterial low-copy number plasmids utilize the ParA/ParB partition system for segregation.
  • Previous models proposed filament-based motility for ParA/ParB, but recent data suggest a diffusion ratchet mechanism.

Purpose of the Study:

  • To develop a theoretical model for ParA/ParB-mediated DNA motility.
  • To elucidate the detailed mechanism driving directed and persistent movement of DNA cargo.
  • To understand how nonmotor proteins collectively propel DNA in bacteria.

Main Methods:

  • Theoretical modeling of the ParA/ParB system.
  • Analysis of ATPase-dependent cycling of ParA-nucleoid affinity.
  • Investigation of transient tethering to the nucleoid surface.

Main Results:

  • The ParA/ParB system functions as a Brownian ratchet.
  • Mechanochemical coupling drives directed motion of ParB-bound cargo.
  • Processive motion results from quenching diffusion via numerous transient tethers.

Conclusions:

  • The ParA/ParB system provides an evolutionary solution for DNA segregation in bacteria lacking processive motor proteins.
  • Collective action of nonmotor proteins via mechanochemical coupling propels DNA cargo.
  • The diffusion ratchet mechanism explains directed plasmid movement on the nucleoid surface.
Keywords:
Brownian ratchetParA ATPasemotilitytheoretical model

More Related Videos

Generating Controlled, Dynamic Chemical Landscapes to Study Microbial Behavior10:07

Generating Controlled, Dynamic Chemical Landscapes to Study Microbial Behavior

Published on: January 31, 2020

6.7K
Demonstrating the Simplicity and In Situ Temperature Monitoring of the Mechanochemical Synthesis of Metal Chalcogenides Suitable for Thermoelectrics04:09

Demonstrating the Simplicity and In Situ Temperature Monitoring of the Mechanochemical Synthesis of Metal Chalcogenides Suitable for Thermoelectrics

Published on: August 30, 2024

873

Related Concept Videos

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH301:11

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3

All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
7.9K
Directing Effect of Substituents: ortho–para-Directing Groups01:14

Directing Effect of Substituents: ortho–para-Directing Groups

Ortho–para directors are substituent groups attached to the benzene ring and direct the addition of an electrophile to the positions ortho or para to the substituent. All electron-donating groups are considered ortho–para directors. They donate electrons to the ring and make the ring more electron-rich. The ring is therefore susceptible to the addition of electrophiles. Substituents such as amino, hydroxy, or alkoxy, containing lone pairs on the atom adjacent to the ring, donate...
9.5K
Mechanical Protein Functions01:58

Mechanical Protein Functions

Proteins perform many mechanical functions in a cell. These proteins can be classified into two general categories- proteins that generate mechanical forces and proteins that are subjected to mechanical forces. Proteins providing mechanical support to the structure of the cell, such as keratin, are subjected to mechanical force, whereas proteins involved in cell movement and transport of molecules across cell membranes, such as an ion pump, are examples of generating mechanical force. 
5.9K
Chemotaxis and Direction of Cell Migration01:21

Chemotaxis and Direction of Cell Migration

Cells can detect chemical cues in their environment and reorganize the cytoskeleton to migrate toward them or away from them. This directional migration, called chemotaxis, is essential during embryogenesis and development, immune response, tissue repair and regeneration, and reproduction. These chemical cues can either attract or repel the cell's movement. For example, axon development is determined by a combination of chemoattractants and chemorepellents that direct the growing axon...
6.2K
Directing Effect of Substituents: meta-Directing Groups01:09

Directing Effect of Substituents: meta-Directing Groups

Substituents on the benzene ring that direct an incoming electrophile to undergo substitution at the meta position are called meta directors. All meta directors either have a positive charge on the atom directly bonded to the ring or a partial positive charge. These groups function by withdrawing electrons from the ring through inductive and resonance effects. Consider the carbocation intermediates formed upon the addition of an electrophile on nitrobenzene at the...
6.4K
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes...
11.4K