Staphylococcal enterotoxin B gene is associated with a discrete genetic element

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• The chromosomal location of the Staphylococcus aureus enterotoxin B gene (entB) was previously unknown.
• Staphylococcus aureus produces enterotoxin B (SEB), a key virulence factor.

Purpose of the Study:

• To determine the chromosomal location and genetic context of the enterotoxin B gene (entB) in Staphylococcus aureus.
• To investigate the genetic element associated with SEB production.

Main Methods:

• Southern hybridization analysis of chromosomal DNA from SEB-producing and SEB-nonproducing Staphylococcus aureus strains.
• Comparative analysis of DNA homology across different strains.

Main Results:

• A genetic element of at least 26.8 kilobases (kb) is associated with the enterotoxin B gene (entB).
• The entB gene is located within this element, with one end approximately 1.5 kb downstream of the gene.
• Homologous regions were identified flanking the entB element in both SEB-producing and SEB-nonproducing strains.
• Some SEB-negative strains lacked the entire entB element, indicating its mobile or variable nature.

Conclusions:

• The enterotoxin B gene (entB) resides within a discrete genetic element of at least 26.8 kb.
• This genetic element appears to be integrated into the Staphylococcus aureus chromosome and can be lost in some strains.
• Understanding the genetic basis of SEB production is crucial for controlling S. aureus infections.