Related Experiment Video
Updated: May 10, 2026
08:53
Biochemical and Structural Characterization of the Carbohydrate Transport Substrate-binding-protein SP0092
Published on: October 2, 2017
Structure, biosynthesis, and function of bacterial capsular polysaccharides synthesized by ABC transporter-dependent
Lisa M Willis1, Chris Whitfield
1Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Carbohydrate Research
|June 11, 2013
Summary
Bacterial capsules, crucial for pathogen virulence, are synthesized via ATP-binding cassette (ABC) transporter-dependent pathways. This review details the conserved lipid terminus structure, offering new insights into capsular polysaccharide biosynthesis.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Bacterial capsules, primarily long-chain polysaccharides, are key virulence factors and used in serotyping.
- Capsular polysaccharides (CPSs) synthesized via ATP-binding cassette (ABC) transporter-dependent pathways are common in Gram-negative pathogens like E. coli and N. meningitidis.
- These bacteria are frequently linked to infections such as urinary tract infections, septicemia, and meningitis.
Purpose of the Study:
- This review focuses on CPSs synthesized through ABC transporter-dependent pathways in Gram-negative bacteria.
- It highlights the conserved reducing terminal glycolipid structure and its implications for understanding CPS biosynthesis.
- The review aims to synthesize current knowledge on this specific CPS synthesis mechanism.
Main Methods:
- Review of existing literature on bacterial capsule biosynthesis.
- Focus on Gram-negative bacteria utilizing ABC transporter-dependent pathways.
- Analysis of structural data for conserved glycolipid termini.
Main Results:
- CPSs synthesized via ABC transporter-dependent pathways involve cytoplasmic synthesis and translocation across the inner membrane.
- A conserved reducing terminal glycolipid, comprising phosphatidylglycerol and a Kdo linker, is a hallmark of these CPSs.
- Recent structural discoveries illuminate the initial stages of CPS biosynthesis.
Conclusions:
- The conserved glycolipid terminus is a critical feature of CPSs synthesized via ABC transporter-dependent pathways.
- Understanding this terminus provides novel insights into the early steps of capsular polysaccharide assembly.
- This knowledge is vital for studying virulence mechanisms and developing potential therapeutic strategies against relevant pathogens.
Keywords:
ABC transportersBiosynthesisCapsular polysaccharidesExportGlycosyltransferasesGram-negative bacteriaMore Related Videos
Related Concept Videos
01:19Formation of Lipopolysaccharides
Lipopolysaccharides (LPS) are crucial components of the outer membrane of Gram-negative bacteria, serving both structural and functional roles. It contributes to membrane stability and protects bacteria from host immune responses. LPS is composed of three major regions—lipid A, a core oligosaccharide, and an O antigen. The biosynthesis and assembly of LPS involve a highly coordinated set of enzymatic reactions and transport mechanisms. Additionally, LPS is recognized as an endotoxin, triggering...
01:18Outer Layers of the Cell Envelope
The outermost layers of prokaryotic cells play a critical role in their survival, virulence, and interaction with the environment. These layers, often composed of polysaccharides, polypeptides, or proteins, form protective and adhesive structures that vary in organization and function.Capsules and Slime LayersCapsules are highly organized, tightly bound layers that firmly attach to the bacterial cell wall. Capsules are usually made of polysaccharides, though some are made of polypeptides. These...
01:24Biosynthesis in Bacteria
Biosynthesis in bacteria is a fundamental anabolic process that generates essential macromolecules, including proteins, nucleic acids, lipids, and polysaccharides. These macromolecules are critical for cellular growth, replication, and function. The process is tightly regulated and energetically linked to catabolic pathways to ensure optimal resource utilization.Biosynthetic pathways begin with precursor metabolites such as pyruvate, acetyl-CoA, and glucose-6-phosphate derived from glycolysis,...
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...
01:17Gram-negative Bacterial Protein Secretion Systems
Gram-negative bacteria utilize sophisticated protein secretion systems to transport proteins across their double-membrane envelope into the extracellular environment or host cells. Based on their mechanism of action, these systems are classified into one-step and two-step pathways.One-Step Secretion Systems (Types I, III, IV, and VI)One-step secretion systems bypass the periplasm entirely, forming a continuous channel that spans both the inner and outer membranes:Type I Secretion System (T1SS):...
01:27ABC Transporters: Importer
ATP-binding cassette or ABC transporters are a class of ATP-driven pumps that hydrolyze ATP to move solutes across the membrane. They can be grouped into importers and exporters. While exporters are present in all domains of life, importers exist only in bacteria and some plants.
In bacteria, based on the number of transmembrane helices and the chemical nature of their substrates, the ABC importers can be divided into three types:
In bacteria, based on the number of transmembrane helices and the chemical nature of their substrates, the ABC importers can be divided into three types: