The non-pathogenic Escherichia coli strain W secretes SslE via the virulence-associated type II secretion system beta

BMC Microbiology

Rembrandt J F Haft¹  Robert Landick³  Mark S DeCanio² 

[1] Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, USA;Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA;Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, USA

关键词: Colonization factor;    Escherichia coli;    Surface display;    Type II secretion;   

Others  :  1143647
DOI  :  10.1186/1471-2180-13-130

 received in 2013-03-11, accepted in 2013-06-04,  发布年份 2013

【 摘 要 】

Background

Many pathogenic E. coli strains secrete virulence factors using type II secretory systems, homologs of which are widespread in Gram-negative bacteria. Recently, the enteropathogenic Escherichia coli strain E2348/69 was shown to secrete and surface-anchor SslE, a biofilm-promoting virulence factor, via a type II secretion system. Genes encoding SslE and its associated secretion system are conserved in some non-pathogenic E. coli, including the commonly-used W (Waksman) strain.

Results

We report here that E. coli W uses its type II secretion system to export a cognate SslE protein. SslE secretion is temperature- and nutrient-dependent, being robust at 37°C in rich medium but strongly repressed by lower temperatures or nutrient limitation. Fusing either of two glycosyl hydrolases to the C-terminus of SslE prevented it from being secreted or surface-exposed. We screened mutations that inactivated the type II secretion system for stress-related phenotypes and found that inactivation of the secretion system conferred a modest increase in tolerance to high concentrations of urea. Additionally, we note that the genes encoding this secretion system are present at a hypervariable locus and have been independently lost or gained in different lineages of E. coli.

Conclusions

The non-pathogenic E. coli W strain shares the extracellular virulence factor SslE, and its associated secretory system, with pathogenic E. coli strains. The pattern of regulation of SslE secretion we observed suggests that SslE plays a role in colonization of mammalian hosts by non-pathogenic as well as pathogenic E. coli. Our work provides a non-pathogenic model system for the study of SslE secretion, and informs future research into the function of SslE during host colonization.

【 授权许可】

   
2013 DeCanio et al.; licensee BioMed Central Ltd.

【 图 表 】

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