Related Experiment Video

Updated: Aug 2, 2026

The Multifaceted Benefits of Protein Co-expression in Escherichia coli
12:48

The Multifaceted Benefits of Protein Co-expression in Escherichia coli

Published on: February 5, 2015

Genetic basis of the MbrC "ploidy" phenotype in Escherichia coli

A M Estévenon1, M Lemonnier, C Rouquette

  • 1Laboratoire de Microbiologie et Génétique Moléculaire, CNRS, Toulouse, France.

Molecular & General Genetics : MGG
|December 11, 1997
PubMed

Insights

The MbrC17 mutation in Escherichia coli causes conditional growth defects by increasing secE-nusG mRNA levels. This genetic study identified a specific G-to-A mutation upstream of the secE gene responsible for the observed phenotype.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • The MbrC17 mutation in Escherichia coli is associated with conditional growth defects and increased DNA content per cell.
  • Previous hypotheses suggested the mutation involved the glr (murI) gene, but this was not supported by current findings.

Purpose of the Study:

  • To identify the precise genetic mutation responsible for the MbrC17 phenotype in Escherichia coli.
  • To elucidate the molecular mechanism underlying the growth defects and increased DNA quantity.

Main Methods:

  • DNA sequencing was employed to analyze the genetic alterations in the MbrC17 strain.
  • P1 transduction experiments were conducted to map the mutation's genetic location.
  • Allele exchange was utilized to confirm the mutation's precise position within the secE-nusG operon.

Main Results:

  • Sequencing revealed a single G-to-A mutation located 23 base pairs upstream of the secE coding sequence within the secE-nusG operon.
  • The identified mutation was found to be closely linked to the rpoB gene.
  • This specific mutation resulted in a two-fold increase in the concentration of secE-nusG mRNA.

Conclusions:

  • The MbrC17 phenotype is caused by a mutation upstream of the secE gene, not involving glr (murI).
  • The mutation leads to elevated secE-nusG mRNA levels, suggesting a regulatory role in gene expression.
  • This finding provides a molecular basis for the observed growth defects in Escherichia coli.

More Related Videos

Manipulation of Ploidy in Caenorhabditis elegans07:54

Manipulation of Ploidy in Caenorhabditis elegans

Published on: March 15, 2018

Producing Gene Deletions in Escherichia coli by P1 Transduction with Excisable Antibiotic Resistance Cassettes08:13

Producing Gene Deletions in Escherichia coli by P1 Transduction with Excisable Antibiotic Resistance Cassettes

Published on: September 1, 2018

Related Concept Videos

Position-effect Variegation02:32

Position-effect Variegation

In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
Nondisjunction01:21

Nondisjunction

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate correctly and move to the opposite poles of the cells. This produces daughter cells with abnormal chromosome numbers.  Nondisjunction is common during anaphase I or anaphase II of meiosis.  Mutations in synaptonemal complex proteins that attach homologous chromosomes increase the chances of nondisjunction in anaphase I of meiosis I. In contrast, mutations in topoisomerases and condensins that hold sister...
Coordination of Gene Expression Processes in Bacteria01:29

Coordination of Gene Expression Processes in Bacteria

The DNA replication, transcription, and translation processes are intricately coupled in bacteria, allowing efficient gene expression and rapid protein synthesis. While this physical and functional coordination is advantageous, it introduces challenges that bacteria overcome through specific regulatory mechanisms.Coupling of Replication, Transcription, and TranslationThe coupling of replication, transcription, and translation is a hallmark of bacterial gene expression. As the replisome unwinds...
Stringent Response in E. coli01:23

Stringent Response in E. coli

Bacterial growth is closely tied to nutrient availability, with cells proliferating exponentially under favorable conditions and entering a stationary phase when resources become scarce. This transition is mediated by a regulatory mechanism known as the stringent response, which allows bacteria to adapt to nutrient deprivation by modulating gene expression and metabolic activity.During nutrient scarcity, intracellular amino acid levels decline. It results in the accumulation of uncharged tRNAs...
Plasmids01:28

Plasmids

Plasmids are extrachromosomal DNA molecules found in bacteria, archaea, and some eukaryotic microbes like yeast. These small, circular DNA structures typically contain fewer than 30 genes, although some may exist linearly. Plasmids vary in their number within a cell, known as copy number. Single-copy plasmids are present in one copy per cell and multi-copy plasmids are present in multiple copies, reaching over 100 copies per cell.Plasmids usually replicate independently of the chromosomal DNA...