sae is essential for expression of the staphylococcal adhesins Eap and Emp

1 Institute of Medical Microbiology and Hygiene, Building 43, University of Saarland, D-66421 Homburg/Saar, Germany 2 Institute of Molecular Biology, Center of Excellence for Molecular Medicine, Slovak Academy of Sciences, 845 51 Bratislava, Slovak Republic 3 Institute of Medical Microbiology and Hygiene, University of Tübingen, D-72074 Tübingen, Germany 4 Institute of Molecular Infection Biology, University of Würzburg, D-97070 Würzburg, Germany 5 Institute of Infection, Immunity and Inflammation, University of Nottingham, Nottingham NG7 2RD, UK 6 School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington LE12 5RD, UK Correspondence Niamh Harraghy bhnhar{at}uniklinik-saarland.de Eap and Emp are two Staphylococcus aureus adhesins initially described as extracellular matrix binding proteins. Eap has since emerged as being important in adherence to and invasion of eukaryotic cells, as well as being described as an immunomodulator and virulence factor in chronic infections. This paper describes the mapping of the transcription start point of the eap and emp promoters. Moreover, using reporter-gene assays and real-time PCR in defined regulatory mutants, environmental conditions and global regulators affecting expression of eap and emp were investigated. Marked differences were found in expression of eap and emp between strain Newman and the 8325 derivatives SH1000 and 8325-4. Moreover, both genes were repressed in the presence of glucose. Analysis of expression of both genes in various regulatory mutants revealed that sarA and agr were involved in their regulation, but the data suggested that there were additional regulators of both genes. In a sae mutant, expression of both genes was severely repressed. sae expression was also reduced in the presence of glucose, suggesting that repression of eap and emp in glucose-containing medium may, in part, be a consequence of a decrease in expression of sae . Abbreviations: FnBP, fibronectin-binding protein; TSP, transcription start point