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Identity of macromolecules present in the extracellular slime layer of Staphylococcus epidermidis
N K Karamanos1, H S Panagiotopoulou, A Syrokou
1Department of Chemistry, University of Patras, Greece.
Abstract:
The extracellular slime layer of Staphylococcus epidermidis ATCC 35983 contains: a) two non-anionic carbohydrate containing proteins degradable with papain of molecular masses 250 and 125 kDa; b) a polydisperse but homogeneously-charged acidic population with M(r) ranging from 120,000 to 35,000 (average M(r) (80,000) containing a polysaccharide covalently bound to a small peptide; c) a papain degradable macromolecule (molecular mass 60 kDa) bearing acidic carbohydrates covalently bound to protein; and c) two acidic polysaccharides strongly retained by the anion-exchange column; one polysaccharide is sulphated and has a molecular mass of 20 kDa; the other has a higher charge density and a molecular mass of 12.5 kDa. The results obtained clearly demonstrate the presence of discrete macromolecules in the extracellular material of slime-producing S epidermidis, the majority of which contain acidic carbohydrates, whose biological role remains to be elucidated.
Insights
The extracellular slime layer of Staphylococcus epidermidis contains various carbohydrate-protein macromolecules. Further research is needed to understand the biological role of these acidic carbohydrates in slime production.
Area of Science:
- Microbiology
- Biochemistry
- Extracellular Matrix Research
Background:
- Staphylococcus epidermidis is a common bacterium known for producing an extracellular slime layer.
- The composition and structure of this slime layer are crucial for understanding bacterial adhesion and biofilm formation.
- Previous studies have indicated the presence of complex carbohydrates within the slime layer, but detailed characterization is limited.
Purpose of the Study:
- To comprehensively characterize the macromolecular components of the extracellular slime layer of Staphylococcus epidermidis ATCC 35983.
- To identify and describe the molecular masses and properties of proteins, polysaccharides, and their conjugates within the slime.
- To lay the groundwork for future investigations into the functional significance of these components.
Main Methods:
- Enzymatic degradation using papain to assess protein components.
- Size exclusion chromatography and anion-exchange chromatography to analyze molecular mass and charge properties.
- Characterization of carbohydrate and protein moieties within the isolated macromolecules.
Main Results:
- Identification of two papain-degradable proteins (250 and 125 kDa) lacking anionic charges.
- Characterization of an acidic macromolecular population (average M(r) 80,000) comprising a polysaccharide covalently linked to a peptide.
- Detection of a papain-degradable macromolecule (60 kDa) with covalently bound acidic carbohydrates and proteins.
- Isolation of two distinct acidic polysaccharides: a 20 kDa sulfated polysaccharide and a 12.5 kDa polysaccharide with higher charge density.
Conclusions:
- The extracellular slime of Staphylococcus epidermidis ATCC 35983 is composed of discrete macromolecules, predominantly containing acidic carbohydrates.
- These acidic carbohydrate-containing macromolecules represent significant components of the bacterial extracellular matrix.
- The specific biological functions of these identified macromolecules, particularly the acidic carbohydrates, require further elucidation.