Related Experiment Video

Updated: Jul 14, 2026

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
11:27

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050

Published on: May 13, 2020

The C-terminal region of Escherichia coli MutS and protein oligomerization

Virginia Miguel1, Roberto J Pezza, Carlos E Argaraña

  • 1Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina.

Biochemical and Biophysical Research Communications
|June 30, 2007
PubMed

Insights

The C-terminal region of Escherichia coli MutS protein is crucial for its tetramer formation and DNA repair function. Deleting key C-terminal amino acids disrupts MutS oligomerization and leads to hypermutation in cells.

Area of Science:

  • Molecular Biology
  • Genetics
  • Protein Biochemistry

Background:

  • Escherichia coli MutS is an oligomeric protein essential for postreplicative DNA mismatch repair.
  • MutS also plays a role in preventing homeologous recombination.
  • Understanding MutS oligomerization is key to its function in DNA repair.

Purpose of the Study:

  • To investigate the role of the C-terminal region of Escherichia coli MutS in protein oligomerization.
  • To determine the specific amino acid residues critical for MutS tetramer formation and stability.
  • To assess the in vivo significance of the C-terminal region in DNA repair.

Main Methods:

  • Site-directed mutagenesis of the C-terminal region of MutS.
  • Construction and expression of chimeric proteins (MutS C-terminus/HTH domain fused to Maltose Binding Protein).
  • Chemical cross-linking experiments to assess protein oligomerization.
  • Analysis of hypermutator phenotype in E. coli expressing chimeric proteins.

Main Results:

  • Deletion of the final 7 C-terminal amino acids abolished MutS tetramer formation.
  • Substitution of Lysine at position 850 (K850A) destabilized the tetramer structure.
  • The C-terminal alpha helix (residues 839-850) is proposed to be vital for oligomerization.
  • Chimeric proteins containing the MutS C-terminal region or C-terminus plus HTH domain promoted oligomerization.
  • The HTH domain enhanced the oligomerization properties of fused proteins.
  • E. coli cells expressing these chimeric proteins exhibited a hypermutator phenotype.

Conclusions:

  • The C-terminal region of Escherichia coli MutS is essential for its oligomerization and DNA repair functions.
  • Specific C-terminal residues, including the extreme alpha helix, are critical for maintaining the tetrameric structure.
  • The C-terminal region's role in vivo is significant, as evidenced by the hypermutator phenotype.
  • The HTH domain contributes to, but is not solely responsible for, the oligomerization-promoting activity of the C-terminus.

More Related Videos

Site-Directed Mutagenesis for In Vitro and In Vivo Experiments Exemplified with RNA Interactions in Escherichia Coli07:04

Site-Directed Mutagenesis for In Vitro and In Vivo Experiments Exemplified with RNA Interactions in Escherichia Coli

Published on: February 5, 2019

The Multifaceted Benefits of Protein Co-expression in Escherichia coli12:48

The Multifaceted Benefits of Protein Co-expression in Escherichia coli

Published on: February 5, 2015

Related Concept Videos

Mismatch Repair01:20

Mismatch Repair

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
Mismatch Repair01:36

Mismatch Repair

Overview
Export of Misfolded Proteins out of the ER01:32

Export of Misfolded Proteins out of the ER

After folding, the ER assesses the quality of secretory and membrane proteins. The correctly folded proteins are cleared by the calnexin cycle for transport to their final destination, while misfolded proteins are held back in the ER lumen. The ER chaperones attempt to unfold and refold the misfolded proteins but sometimes fail to achieve the correct native conformation. Such terminally misfolded proteins are then exported to the cytosol by ER-associated degradation or ERAD pathway for...
Bacterial Protein Maturation01:26

Bacterial Protein Maturation

Bacterial protein maturation is a tightly regulated process that ensures newly synthesized polypeptides achieve correct functional conformations. This maturation involves a series of modifications, folding events, and quality control steps, often assisted by specialized chaperone proteins.N-Terminal ModificationsThe maturation of bacterial polypeptides begins cotranslationally as the polypeptide exits the ribosome. The first amino acid, N-formylmethionine (fMet), is typically modified at the...
Molecular Chaperones and Protein Folding03:00

Molecular Chaperones and Protein Folding

The native conformation of a protein is formed by interactions between the side chains of its constituent amino acids. When the amino acids cannot form these interactions, the protein cannot fold by itself and needs chaperones. Notably, chaperones do not relay any additional information required for the folding of polypeptides; the native conformation of a protein is determined solely by its amino acid sequence. Chaperones catalyze protein folding without being a part of the folded protein.
The...
Protein Modifications in the RER01:26

Protein Modifications in the RER

Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.