Related Experiment Video

Updated: Jul 10, 2026

Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility
12:29

Generation of Null Mutants to Elucidate the Role of Bacterial Glycosyltransferases in Bacterial Motility

Published on: March 11, 2022

Conditional lethality, division defects, membrane involution, and endocytosis in mre and mrd shape mutants of

Felipe O Bendezú1, Piet A J de Boer

  • 1Case Western Reserve University, School of Medicine, Department of Molecular Biology and Microbiology, Cleveland, OH 44106, USA.

Journal of Bacteriology
|November 13, 2007
PubMed

Insights

Loss of Escherichia coli shape proteins causes cells to form spheres and develop internal membrane compartments. Extra FtsZ protein rescues viability, preventing lethal division defects in these shape mutants.

Area of Science:

  • Microbiology
  • Cell Biology
  • Bacterial Cytoskeleton

Background:

  • Bacterial rod shape maintenance in Escherichia coli relies on MreB-actin cytoskeleton and associated proteins like MreC, MreD, PBP2 (MrdA), and RodA (MrdB).
  • The impact of losing these essential shape proteins on E. coli viability and cell division has remained largely unknown.

Purpose of the Study:

  • To investigate the viability and morphological consequences of depleting essential shape proteins (MreB, MreC, MreD, MrdA, MrdB) in Escherichia coli.
  • To elucidate the role of FtsZ in cell division and the formation of intracellular structures in the absence of proper cell shape maintenance.

Main Methods:

  • Generation of depletion strains for Mre and Mrd proteins under low selective pressure.
  • Microscopy techniques to observe cell morphology, FtsZ assembly, and intracellular membrane structures.
  • Analysis of phospholipid synthesis rates in response to shape protein depletion.

Main Results:

  • Depletion of Mre or Mrd proteins resulted in viable cells propagating as spheres, forming large nondividing spheroids at higher growth rates.
  • Excess FtsZ protein suppressed lethality and allowed spherical propagation under all conditions.
  • Mutants exhibited complex, membrane-bound intracellular compartments formed by cytoplasmic membrane involution, with some appearing released into the cytoplasm.
  • Cells failed to adjust phospholipid synthesis, leading to excess membrane in spheroids.
  • FtsZ and MinD assembled on intracytoplasmic membranes, potentially blocking cell division.

Conclusions:

  • Escherichia coli lacking key shape proteins can survive as spheres but face division failure due to aberrant membrane structures and protein assembly.
  • FtsZ plays a critical role in overcoming division defects caused by shape protein loss.
  • Intracytoplasmic membrane formation and impaired phospholipid regulation contribute to the lethality observed in these bacterial shape mutants.

More Related Videos

Mapping Bacterial Functional Networks and Pathways in Escherichia Coli using Synthetic Genetic Arrays14:06

Mapping Bacterial Functional Networks and Pathways in Escherichia Coli using Synthetic Genetic Arrays

Published on: November 12, 2012

Quantitative Approaches for Studying Cellular Structures and Organelle Morphology in Caenorhabditis elegans08:47

Quantitative Approaches for Studying Cellular Structures and Organelle Morphology in Caenorhabditis elegans

Published on: July 5, 2019

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 Gastroenteritis01:18

Bacterial Gastroenteritis

Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...
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...