Related Experiment Video
Updated: Jul 9, 2026
09:09
Semi-Quantitative Analysis of Peptidoglycan by Liquid Chromatography Mass Spectrometry and Bioinformatics
Published on: October 13, 2020
Stabilizing isopeptide bonds revealed in gram-positive bacterial pilus structure
Hae Joo Kang1, Fasséli Coulibaly, Fiona Clow
1Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Auckland 1010, New Zealand.
Science (New York, N.Y.)
|December 8, 2007
Summary
Researchers determined the crystal structure of Streptococcus pyogenes pili, revealing how isopeptide bonds create strong, stable bacterial adhesion structures. This finding could aid in developing new vaccines against this pathogen.
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Many bacterial pathogens utilize pili for host cell adhesion.
- Gram-positive bacteria like Streptococcus pyogenes possess long, slender pili crucial for virulence.
Purpose of the Study:
- To elucidate the molecular structure of the major pilin subunit from Streptococcus pyogenes.
- To understand the mechanism behind the strength and stability of Gram-positive pili.
Main Methods:
- X-ray crystallography at 2.2 angstrom resolution.
- Analysis of molecular assembly and intermolecular interactions.
Main Results:
- The crystal structure reveals an extended, two all-beta domain pilin subunit.
- Subunits associate in columns via isopeptide bonds between carboxyl termini and conserved lysine residues.
- Intramolecular lysine-asparagine isopeptide bonds were identified within each subunit.
- Evidence suggests similar isopeptide bonds in other Gram-positive bacterial cell surface proteins.
Conclusions:
- The determined structure explains the inherent strength and stability of Gram-positive pili.
- Understanding pilus structure and assembly may facilitate the development of novel vaccines against Streptococcus pyogenes.
More Related Videos
Related Concept Videos
01:29Cytoskeletal Proteins in Bacteria
Bacterial cells were initially considered simple, randomly organized structures lacking a cytoskeleton. However, the discovery of cytoskeleton homologs in bacteria led to the change of this opinion. Bacterial cytoskeletal filaments regulate the cell shape, cell polarity, cell division, and partitioning of plasmids during cell division. It was later discovered that bacterial cytoskeletal proteins, mainly actin and tubulin homologs, are diverse compared to their eukaryotic counterparts. On the...
01:28Fimbriae, Pili, and Axial Filaments
Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
01:28Peptidoglycan Synthesis
Structure of PeptidoglycanPeptidoglycan is a vital structural component of the bacterial cell wall, providing mechanical strength and shape to the cell. It consists of repeating units of two sugars—N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)—linked by β-1,4 glycosidic bonds. These sugar chains are cross-linked by short peptide chains, forming a mesh-like polymer that surrounds the bacterial plasma membrane.Cytoplasmic Phase – Precursor SynthesisPeptidoglycan biosynthesis begins in...
01:23Inhibitors of Gram-positive Cell Wall Synthesis
Bacterial cell walls are typically rigid structures composed mainly of peptidoglycan, a mesh-like polymer that provides mechanical strength and maintains cell shape. The synthesis of peptidoglycan is a crucial process in bacterial growth and serves as a primary target for many antibiotics.Mechanism of Action of Beta-Lactam AntibioticsBeta-lactam antibiotics, such as penicillin, inhibit peptidoglycan synthesis in actively growing cells. These antibiotics share a characteristic four-membered...
01:22Protein Folding
Overview
01:25Protein Folding
Proteins are chains of amino acids linked together by peptide bonds. Upon synthesis, a protein folds into a three-dimensional conformation, critical to its biological function. Interactions between its constituent amino acids guide protein folding, and hence the protein structure is primarily dependent on its amino acid sequence.
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...
Protein Structure Is Critical to Its Biological Function
Proteins perform a wide range of biological functions such as catalyzing chemical reactions, providing...