Related Experiment Video

Updated: Aug 29, 2026

Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification
10:21

Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification

Published on: November 16, 2016

Features of the plasmid pMV158-encoded MobM, a protein involved in its mobilization

Carmen de Antonio1, María Eugenia Farías, Mario García de Lacoba

  • 1Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Velazquez, 144, E-28006 Madrid, Spain.

Journal of Molecular Biology
|December 23, 2003
PubMed

Insights

The MobM protein from the pMV158 plasmid is crucial for bacterial conjugation, acting as a relaxase. Structural analysis reveals MobM functions as a membrane-associated dimer with significant alpha-helical content.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • The streptococcal plasmid pMV158 facilitates bacterial conjugation across species.
  • Conjugation relies on the MobM protein (a relaxase), the oriT(pMV158) DNA site, and auxiliary plasmids.
  • MobM belongs to the Pre/Mob family of plasmid-encoded DNA-relaxing enzymes.

Purpose of the Study:

  • To characterize the structural and biochemical properties of the MobM protein.
  • To investigate the role of MobM in plasmid mobilization and its cellular localization.
  • To develop a molecular model for MobM based on existing protein structures.

Main Methods:

  • Purified MobM protein was used to assay DNA cleavage conditions.
  • Analytical ultracentrifugation, circular dichroism, and thermal denaturation were employed for structural analysis.
  • Cell fractionation and fluorescence emission were used to determine protein localization and environment.

Main Results:

  • MobM functions as an ellipsoidal dimer with approximately 60% alpha-helical content.
  • The protein exhibits a midpoint denaturation temperature of around 40°C.
  • MobM associates with the cell membrane, a function dependent on its C-terminal coiled-coil region.

Conclusions:

  • MobM is a structurally characterized relaxase essential for pMV158 plasmid mobilization.
  • Its dimeric, membrane-associated nature and alpha-helical structure are key to its function.
  • The study provides insights into the mechanism of bacterial conjugation and MobM's role within it.

More Related Videos

Identification of Plasmodesmal Localization Sequences in Proteins In Planta08:07

Identification of Plasmodesmal Localization Sequences in Proteins In Planta

Published on: August 15, 2017

Preparation of the Mgm101 Recombination Protein by MBP-based Tagging Strategy11:40

Preparation of the Mgm101 Recombination Protein by MBP-based Tagging Strategy

Published on: June 25, 2013

Related Concept Videos

Intracellular Movement of Viruses and Bacteria01:10

Intracellular Movement of Viruses and Bacteria

Intracellular bacteria and viruses often comprise a group of highly infectious pathogens that can cause several diseases. Bacterial pathogens include those belonging to the genus Rickettsia responsible for conditions such as rocky mountain spotted fever and the Mediterranean spotted fever; Chlamydia, a genus responsible for a sexually transmitted disease; Coxiella burnetii, an agent responsible for Q fever. Viral pathogens include vaccinia—a poxvirus, and herpes simplex virus—a virus that...
Microtubule Associated Proteins (MAPs)01:42

Microtubule Associated Proteins (MAPs)

Microtubule function and architecture are regulated by an array of specialized proteins called microtubule-associated proteins or MAPs. These proteins are widespread across different organisms and have conserved protein motifs, like the multi-TOG domain for tubulin binding found in the CLASP family of MAPs. Some MAPs are lineage-specific based on their conserved domains. Their functions depend upon the cytoskeletal architecture and cell type they are located within. In-plant cells, a specific...
Microtubule Associated Motor Proteins01:32

Microtubule Associated Motor Proteins

Eukaryotic cells have different motor proteins for transporting various cargo within the cell. These motor proteins differ based on the filament they associate with, the direction they move within the cell, and the type of cargo they transport. Motor proteins that associate with microtubules are known as microtubule-associated motor proteins. There are two families of microtubule-associated motor proteins —Kinesins and Dyneins. Both these proteins assist in the transport of cellular cargos...
Translocation of Proteins into the Mitochondria01:19

Translocation of Proteins into the Mitochondria

Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
DNA Bacteriophages01:26

DNA Bacteriophages

Bacteriophages, or phages, are viruses that specifically infect bacteria, utilizing their genetic material to hijack host cellular machinery for replication. DNA bacteriophages employ single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA) genomes. These phages exhibit diverse replication strategies and host interactions, influencing their ecological roles and applications in biotechnology and medicine.ssDNA BacteriophagesssDNA phages, with their small genomes, utilize unique strategies to...
Regulated mRNA Transport02:22

Regulated mRNA Transport

In eukaryotes, transcription and translation are compartmentalized; an mRNA is first synthesized in the nucleus and then selectively transported to the cytoplasm for protein synthesis. Before transport, a pre-mRNA undergoes several steps of post-transcriptional modifications including splicing, 5' capping, and the addition of a poly-adenine tail. Various proteins bind to the pre-mRNA during these modifications. The mRNA transport takes place with the help of multiple proteins playing specific...