cellular response to cell envelope stress

Definition

Target type: biologicalprocess

Any process that results in a change in state or activity of a cell (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of stress acting at the cell envelope. [GOC:imk, PMID:15101969, PMID:15882407]

Cellular response to cell envelope stress is a critical process that allows organisms to maintain cell wall integrity and survival in the face of environmental challenges. The cell envelope, a complex structure composed of the cell wall, outer membrane (in Gram-negative bacteria), and plasma membrane, serves as a barrier against external stresses, including osmotic pressure, pH fluctuations, and antimicrobial agents. When the cell envelope experiences disruptions or damage, various signaling pathways are activated to trigger a coordinated response that aims to restore homeostasis.

The detection of cell envelope stress is initiated by the activation of sensor proteins, often located within the cell envelope itself. These sensors can be transmembrane proteins, such as the two-component system (TCS) receptors, or cytoplasmic proteins that interact with cell envelope components. Upon sensing stress, these proteins undergo conformational changes, which trigger downstream signaling events.

One of the key signaling pathways involved in cellular response to cell envelope stress is the TCS. TCSs are widespread in bacteria and consist of two main components: a sensor histidine kinase (HK) and a response regulator (RR). The HK senses the stress signal and autophosphorylates itself at a histidine residue. The phosphate group is then transferred to the RR, which activates its DNA-binding activity. Activated RRs can then bind to specific promoter regions in the genome, regulating the expression of genes involved in stress response.

Another important signaling pathway is the envelope stress response (ESR) pathway. The ESR pathway is primarily activated by disruptions in the peptidoglycan layer, a major component of the bacterial cell wall. The detection of peptidoglycan fragments, such as muropeptides, triggers the activation of the ESR pathway, leading to the induction of various stress response genes.

The cellular response to cell envelope stress involves a complex interplay of different mechanisms, including:

- **Cell wall biosynthesis and repair:** To maintain cell wall integrity, bacteria activate pathways that promote the synthesis of new cell wall components and repair damaged regions. This involves the production of enzymes involved in peptidoglycan synthesis, such as penicillin-binding proteins (PBPs), as well as enzymes responsible for the breakdown and recycling of existing cell wall components.

- **Stress-specific gene expression:** Cells activate the expression of genes encoding proteins that help to counteract the specific stressor. For instance, in response to osmotic stress, bacteria might upregulate genes involved in the production of osmolytes, small molecules that help to stabilize the cell envelope.

- **Antimicrobial resistance:** Some bacteria have evolved mechanisms to resist the action of antimicrobial agents that target the cell envelope. These mechanisms include the production of efflux pumps that remove antibiotics from the cell, modifications of drug targets to reduce their sensitivity, and the synthesis of enzymes that inactivate antibiotics.

- **Regulation of cell division:** In severe cases of cell envelope stress, bacteria might arrest cell division to allow for time to repair the damage. This ensures that the damage is not propagated to daughter cells.

The specific response to cell envelope stress varies depending on the type of stress, the organism, and the environment. However, the general principles of sensing, signaling, and gene expression are conserved across diverse bacterial species. Understanding the cellular response to cell envelope stress is essential for developing new strategies to combat bacterial infections, as well as for engineering bacteria for industrial applications.'
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Proteins (4)

Compounds (2)