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#bacterial structure

7 public questions tagged with this topic.

Microbial Physiology

What is the function of Teichoic acids in Gram-positive bacteria?

Wall teichoic acids covalently attached to peptidoglycan via phosphodiester to N-acetylmuramic acid and lipoteichoic acids anchored to membrane diacylglycerol through glycolipid are hallmark anionic glycopolymers of Gram-positive envelope, comprising up to 60 percent of wall dry weight. Their polyanionic phosphate backbone creates high density of negative charge at surface, enabling binding of divalent cations like magnesium and calcium, concentrating them near membrane for activity of enzymes and protection against cationic antimicrobial peptides. By controlling local ionic environment, teich

Ref: Brown et al., Ann Rev Microbiol 2013, Teichoic Acids; Percy & Grundling, Ann Rev Microbiol 2014, LTA Functions.

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Microbial Physiology

Which bacterial structure prevents plasmolysis in hypertonic conditions?

Hypertonic surroundings draw water out of bacterial cytoplasm through semipermeable inner membrane, generating inward osmotic pressure that tends to detach inner membrane from wall and shrink cytoplasm, a process termed plasmolysis. Survival depends on mechanical resistance supplied by peptidoglycan, a covalently crosslinked heteropolymer forming a single macromolecule sacculus surrounding entire cell, often described as exoskeleton. Its glycan strands crosslinked via peptide bonds possess high tensile strength, allowing it to withstand internal turgor of 2 to5 atmospheres in Gram-negatives an

Ref: Rojas et al., PNAS 2014, Stiffness of Bacterial Cell Wall; Alberts et al., Molecular Biology Cell, Cell Wall Mechanics.

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Microbial Physiology

The MreB cytoskeletal protein plays a role in:

MreB is a widely distributed bacterial homolog of eukaryotic actin conserved across rod-shaped bacteria including Escherichia coli, Bacillus subtilis, and Caulobacter crescentus, essential for maintaining cylindrical morphology and coordinating growth. Unlike eukaryotic actin that forms long helical filaments, MreB assembles into short, antiparallel double protofilaments associated with inner face of cytoplasmic membrane in an ATP-dependent manner, often guided by membrane regions enriched in specific phospholipids. Its primary morphogenetic function is to act as a dynamic scaffold organizing

Ref: Burkman et al., Ann Rev Microbiol 2018, MreB and Rod Shape; Errington, Nature Rev Microbiol 2015, Bacterial Cytoskeleton.

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Microbial Physiology

What happens to Gram-negative bacteria when the outer membrane is removed?

Gram-negative bacteria possess a thin peptidoglycan layer confined to the periplasm between the inner cytoplasmic membrane and a distinctive outer membrane containing lipopolysaccharide and trimeric porins. The outer membrane provides substantial mechanical support, contributes to shape maintenance, and functions as a selective barrier against hydrophobic toxins, bile salts, and many antibiotics. When this membrane is disrupted by EDTA, which chelates magnesium and calcium ions that stabilize LPS contacts, or by mild detergents and lysozyme treatment, barrier and load-bearing capacity are lost

Ref: Madigan et al., Brock Biology of Microorganisms, 16th ed., Chapter 3: Bacterial Envelope; Nature 2018, Outer membrane as load-bearing element.

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