Phage-associated differences in staphylococcal enterotoxin A gene (sea) expression correlate with sea allele class | JoVE Visualize

Phage-associated differences in staphylococcal enterotoxin A gene (sea) expression correlate with sea allele class

D W Borst¹, M J Betley

¹Department of Bacteriology, University of Wisconsin, Madison 53706.

Infection and Immunity|January 1, 1994

View abstract on PubMed

Summary

Researchers identified Staphylococcus aureus strains with high or low staphylococcal enterotoxin A (SEA) production. Differences in SEA gene expression were linked to phage-associated factors and a novel SEA allele, but promoter region variations alone did not explain expression levels.

Area of Science:

Microbiology
Molecular Biology
Genetics

Background:

Staphylococcus aureus produces staphylococcal enterotoxin A (SEA), a common cause of food poisoning.
Variations in SEA production levels among different strains are not fully understood.

Purpose of the Study:

To investigate the molecular mechanisms underlying differences in SEA production between high and low SEA-producing Staphylococcus aureus strains.
To identify genetic factors, including phage-associated elements and SEA gene alleles, that contribute to SEA expression variability.

Main Methods:

Identification and characterization of high and low SEA-producing Staphylococcus aureus strains.
Quantification of sea mRNA levels via Northern blot analysis.
Analysis of sea-containing phages and Southern blot hybridization.
Nucleotide sequencing of the sea gene, focusing on the promoter region.

Main Results:

Significant differences in sea mRNA concentration were observed between high and low SEA-producing strains.
Phage-associated factors contributed to differential sea expression, independent of sea gene copy number.
A new allele of the sea gene was identified in a high-producing strain, with sequence variations concentrated in the upstream promoter region.
Despite correlation, promoter sequence differences alone were insufficient to account for altered sea expression levels.

Conclusions:

Staphylococcal enterotoxin A (SEA) production is influenced by both phage-associated elements and variations within the sea gene itself.
While a novel sea allele and its promoter region were identified, further regulatory mechanisms likely govern the observed differences in SEA expression levels in Staphylococcus aureus.