Related Experiment Video

Updated: Aug 15, 2026

Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids
11:56

Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids

Published on: May 4, 2018

Conserved structure and function in the granulysin and NK-lysin peptide family

Charlotte M A Linde1, Susanna Grundström, Erik Nordling

  • 1Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden. charlotte.linde@mtc.ki.se

Infection and Immunity
|September 24, 2005
PubMed

Insights

Granulysin and NK-lysin peptides show similar structures and antimycobacterial activity. Basic residue alterations impact E. coli activity more than Mycobacterium smegmatis, suggesting conserved function in these related proteins.

Area of Science:

  • Microbiology
  • Structural Biology
  • Immunology

Background:

  • Granulysin and NK-lysin are homologous antimicrobial proteins with known antimycobacterial activity.
  • Short loop peptides from these proteins retain antimicrobial properties.
  • Structural similarities suggest conserved function.

Purpose of the Study:

  • To investigate the structure-activity relationship of granulysin, NK-lysin, and chicken NK-lysin loop peptides.
  • To determine the role of basic residues in the antimicrobial activity of these peptides.
  • To compare the activity against Mycobacterium smegmatis and Escherichia coli.

Main Methods:

  • Homology modeling was used to predict peptide structures.
  • Antimicrobial activity was tested against Mycobacterium smegmatis and Escherichia coli.
  • Amino acid substitutions were made to alter the ratio of arginine to lysine.

Main Results:

  • All examined peptides adopted similar secondary and three-dimensional structures.
  • Peptides exhibited comparable activity against Mycobacterium smegmatis but variable activity against Escherichia coli.
  • Altering the ratio of basic residues affected E. coli activity more significantly than M. smegmatis activity.
  • Arginine residues in granulysin were crucial for cytotoxicity but not essential for antimycobacterial activity.

Conclusions:

  • The antibacterial domains of granulysin, NK-lysin, and chicken NK-lysin share conserved 3-D structures.
  • These conserved structures contribute to their functional activity against mycobacteria.
  • Basic residue composition influences the specificity of antimicrobial action, particularly against Gram-negative bacteria like E. coli.

More Related Videos

A Colorimetric Assay that Specifically Measures Granzyme B Proteolytic Activity: Hydrolysis of Boc-Ala-Ala-Asp-S-Bzl05:20

A Colorimetric Assay that Specifically Measures Granzyme B Proteolytic Activity: Hydrolysis of Boc-Ala-Ala-Asp-S-Bzl

Published on: November 28, 2014

A High Yield and Cost-efficient Expression System of Human Granzymes in Mammalian Cells09:16

A High Yield and Cost-efficient Expression System of Human Granzymes in Mammalian Cells

Published on: June 10, 2015

Related Concept Videos

Conserved Binding Sites01:49

Conserved Binding Sites

Many proteins’ biological role depends on their interactions with their ligands, small molecules that bind to specific locations on the protein known as ligand-binding sites. Ligand-binding sites are often conserved among homologous proteins as these sites are critical for protein function.
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally analyses the...
Conservation of Protein Domains Over Different Proteins02:26

Conservation of Protein Domains Over Different Proteins

Protein domains are small structurally independent units that are part of a single amino acid chain.  Although these domains are often structurally independent, they may rely on synergistic effects to perform their functions as part of a larger protein. Protein domains may be conserved within the same organism, as well as across different organisms.
A limited set of protein domains often duplicate and recombine during evolution. These domains can be organized in different combinations to form...
Cytoskeletal Linker Proteins - Plakins01:09

Cytoskeletal Linker Proteins - Plakins

Plakins are large proteins with binding domains for microtubules, microfilaments, intermediate filaments, and membrane-associated protein complexes at cell junctions. Plakin functions are evolutionarily conserved and are primarily involved in organizing the different components of the cytoskeleton by crosslinking them to each other and connecting them to the cell-matrix and cell adhesion complexes. They are also known to interact with signal transducers, serve as scaffolds for signaling...
Lysosomal Hydrolases01:22

Lysosomal Hydrolases

Lysosomes are the site for the degradation of macromolecules and biological polymers released during membrane trafficking events such as secretory, endocytic, autophagic, and phagocytic pathways. The membrane-enclosed area of the lysosome, called the lumen, contains hydrolytic enzymes active in an acidic environment. These acid hydrolases are functional at a pH between 4.5 and 5 and are involved in cellular processes such as cell signaling, energy metabolism, restoration of the plasma membrane,...
What are Proteins?01:55

What are Proteins?

Overview
Protein and Protein Structure02:15

Protein and Protein Structure

Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. Proteins may be structural, regulatory, contractile, or protective. They may serve in transport, storage, or membranes; or they may be toxins or enzymes. Their structures, like their functions, vary greatly. They are all, however, amino acid polymers arranged in a linear sequence.
A protein's shape is critical to its function. For example, an enzyme can...