PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of bmcmicrBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Microbiology
 
BMC Microbiol. 2012; 12: 219.
Published online 2012 September 25. doi:  10.1186/1471-2180-12-219
PMCID: PMC3489787

Characterization of EssB, a protein required for secretion of ESAT-6 like proteins in Staphylococcus aureus

Abstract

Background

Staphylococcus aureus secretes EsxA and EsxB, two small polypeptides of the WXG100 family of proteins. Genetic analyses have shown that production and secretion of EsxA and EsxB require an intact ESAT-6 Secretion System (ESS), a cluster of genes that is conserved in many Firmicutes and encompasses esxA and esxB . Here, we characterize EssB, one of the proteins encoded by the ESS cluster. EssB is highly conserved in Gram-positive bacteria and belongs to the Cluster of Orthologous Groups of protein COG4499 with no known function.

Results

By generating an internal deletion in essB , we demonstrate that EssB is required for secretion of EsxA. We use a polyclonal antibody to identify EssB and show that the protein fractionates with the plasma membrane of S. aureus . Yet, when produced in Escherichia coli, EssB remains mostly soluble and the purified protein assembles into a highly organized oligomer that can be visualized by electron microscopy. Production of truncated EssB variants in wild-type S. aureus confers a dominant negative phenotype on EsxA secretion.

Conclusions

The data presented here support the notion that EssB may oligomerize and interact with other membrane components to form the WXG100-specific translocon in S. aureus .

Keywords: ESAT-6 secretion, ESS, WXG100, EssB, Type 7 secretion, Staphylococcus aureus

Articles from BMC Microbiology are provided here courtesy of BioMed Central