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🦠microbiology review

Lectin

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Lectins are carbohydrate-binding proteins that can recognize and bind to specific sugar moieties on the surface of cells. They play a crucial role in the virulence mechanisms of many eukaryotic pathogens, allowing them to adhere to and invade host cells.

5 Must Know Facts For Your Next Test

  1. Lectins can act as virulence factors by facilitating the adherence of eukaryotic pathogens to host cells, a crucial first step in the infection process.
  2. Many pathogenic fungi, protozoa, and helminths utilize lectin-mediated adhesion to bind to and invade the epithelial cells lining the gastrointestinal, respiratory, or urogenital tracts.
  3. Certain lectins, such as the Gal/GalNAc-specific lectin of Entamoeba histolytica, can trigger host cell signaling pathways that promote pathogen internalization and facilitate intracellular survival.
  4. Lectins may also contribute to virulence by agglutinating host cells, impairing their function, or by masking the pathogen's surface to evade immune recognition.
  5. The carbohydrate-binding specificity of lectins can determine the tropism of eukaryotic pathogens, influencing their ability to infect and colonize specific host tissues.

Review Questions

  • Explain how lectins function as virulence factors for eukaryotic pathogens.
    • Lectins serve as virulence factors for eukaryotic pathogens by facilitating their adherence to host cells. The carbohydrate-binding properties of lectins allow them to recognize and bind to specific sugar moieties on the surface of epithelial cells, which is a crucial first step in the infection process. This lectin-mediated adhesion can then trigger host cell signaling pathways that promote pathogen internalization and intracellular survival. Additionally, some lectins can agglutinate host cells, impairing their function, or mask the pathogen's surface to evade immune recognition.
  • Describe the role of the glycocalyx in lectin-mediated virulence of eukaryotic pathogens.
    • The glycocalyx, a carbohydrate-rich layer covering the exterior of many cells, serves as a binding site for lectins expressed by eukaryotic pathogens. The specific carbohydrate moieties present in the glycocalyx can determine the tropism of a pathogen, influencing its ability to infect and colonize particular host tissues. Pathogens that express lectins with complementary carbohydrate-binding specificity can effectively adhere to and invade the host cells, facilitating the establishment of infection. The interaction between lectins and the glycocalyx is, therefore, a critical component of the virulence mechanisms employed by many eukaryotic pathogens.
  • Analyze how the carbohydrate-binding properties of lectins contribute to the pathogenesis of eukaryotic infections.
    • The carbohydrate-binding specificity of lectins is a key factor in determining the virulence and pathogenesis of eukaryotic infections. By recognizing and binding to specific sugar moieties on the surface of host cells, lectins can mediate the adherence of pathogens, which is a crucial first step in the infection process. This lectin-mediated adhesion can then trigger host cell signaling pathways that facilitate pathogen internalization and intracellular survival. Additionally, the carbohydrate-binding properties of lectins can influence the tropism of eukaryotic pathogens, determining their ability to infect and colonize specific host tissues. Furthermore, some lectins can agglutinate host cells or mask the pathogen's surface to evade immune recognition, further contributing to the virulence of the infection. Understanding the role of lectins in the pathogenesis of eukaryotic infections is, therefore, crucial for developing effective prevention and treatment strategies.