Related Experiment Video

Updated: Jun 2, 2026

Efficient Mammalian Cell Expression and Single-step Purification of Extracellular Glycoproteins for Crystallization
07:08

Efficient Mammalian Cell Expression and Single-step Purification of Extracellular Glycoproteins for Crystallization

Published on: December 23, 2015

Expression, purification and crystallization of the Cmi immunity protein from Escherichia coli

Christin Römer1, Silke I Patzer, Reinhard Albrecht

  • 1Department for Protein Evolution, Max Planck Institute for Developmental Biology, Spemannstrasse 35, D-72076 Tübingen, Germany.

Acta Crystallographica. Section F, Structural Biology and Crystallization Communications
|April 21, 2011
PubMed

Insights

Researchers purified the colicin M immunity protein (Cmi) from Escherichia coli. This protein protects bacteria from colicin M, a toxin that kills related bacteria.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • Bacteriocins, like colicin M, are protein toxins produced by bacteria to kill related species.
  • In Escherichia coli, colicin M targets the periplasm, and self-protection is mediated by a co-expressed immunity protein.

Purpose of the Study:

  • To clone, overexpress, and purify the colicin M immunity protein (Cmi).
  • To analyze the fold and structure of purified Cmi.
  • To obtain crystals of Cmi for structural determination.

Main Methods:

  • Gene cloning and protein overexpression.
  • Protein purification to homogeneity.
  • Activity tests and circular-dichroism spectroscopy for fold analysis.
  • X-ray crystallography for structural determination.

Main Results:

  • Purified Cmi protein was obtained with correct folding confirmed by activity and spectroscopy.
  • Cmi crystals diffracted to 1.9 Å resolution.
  • Crystal packing analysis indicated one monomer per asymmetric unit in the orthorhombic space group C222(1).

Conclusions:

  • The colicin M immunity protein (Cmi) was successfully purified and characterized.
  • Structural insights into Cmi were obtained through X-ray crystallography, revealing its crystal packing and unit-cell parameters.

More Related Videos

Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy08:27

Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy

Published on: January 7, 2019

Method for Efficient Refolding and Purification of Chemoreceptor Ligand Binding Domain14:25

Method for Efficient Refolding and Purification of Chemoreceptor Ligand Binding Domain

Published on: December 12, 2017

Related Concept Videos

Production of Pharmaceuticals01:30

Production of Pharmaceuticals

Industrial insulin production uses genetically engineered E. coli expressing a proinsulin gene controlled by a tryptophan promoter and containing a methionine linker for later cleavage. The cells also carry ampicillin resistance for selective growth. Seed cultures are stored at −80 °C and production begins by thawing a small amount to inoculate starter cultures, which are progressively scaled to a 50,000-L bioreactor. In the bioreactor, E. coli grow in nutrient-rich media under sterile, tightly...
Immunoprecipitation01:20

Immunoprecipitation

Immunoprecipitation, or IP, is a widely used technique that employs protein-antibody interactions to isolate proteins or protein complexes in their native state for studying protein-protein interactions, quaternary structures, or supramolecular complexes. Various modifications of the technique, including chromatin IP, cross-linking IP, and fluorescence IP, are commonly used.
Chromatin Immunoprecipitation
Chromatin immunoprecipitation, also known as ChIP, is used to study protein-DNA or...