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Using E.Coli to study cell wall development in bacteria

Date: 01 December 2019 Tags: Biotechnology

Issue

Researchers have identified an enzyme that plays a crucial role in the enlargement and growth of bacteria, by studying E. coli.

 

Background

One of the most important features of a bacterium is its cell wall which protects it from external environmental conditions and also internal pressure and keeps it in shape. Harming the cell wall causes irreversible damage to the bacterium and eventually kills it.

 

Details

  • The enzyme MepK helps in cutting a particular class of bonds that connect the peptidoglycan, which is a sac-like molecule that envelops the cell.

  • This action allows more material to be added to the cell wall, making a larger compartment for the cell to reside in.

  • The bacteria die when the integrity of the cell wall is destroyed. Its crucial role in maintaining the wellbeing of the bacterium makes the cell wall a target of study, especially by scientists interested in developing new drug strategies to combat the bacteria.

  • Earlier research showed that opening the cell wall by hydrolysing enzymes is crucial for the new material to be incorporated into it, leading to the cell’s expansion and elongation.

  • The cell wall is made up mostly of a single net-like molecule (peptidoglycan) which consists of many sugar polymers interconnected by short peptides. It encloses the bacterial cytoplasmic membrane.

  • The peptides connecting the bag-like structure are cross-linked in several ways. The significance to this work is the link between particular amino acid residues located on adjacent peptide chains.

  • This is a rare component present only in bacterial cell walls and is known as mDAP for short.

  • The group identified an enzyme (MepK) which helps in breaking down the bond between two mDAP residues. This leads to cutting the molecular mesh and thus aiding the growth (or enlargement) of the cell.

  • The study has higher significance in organisms like Clostridia and M. tuberculosis because cell walls of these bacteria have very high levels of mDAP-mDAP type of cross-links. 

  • The next course of experiments would be identifying small-molecule inhibitors for this class of enzymes and also to understand the molecular mechanisms by which the cell wall growth is initiated.