SarA is an essential positive regulator of Staphylococcus epidermidis biofilm development
Fecha
2005Autor
Versión
Acceso abierto / Sarbide irekia
Tipo
Artículo / Artikulua
Versión
Versión publicada / Argitaratu den bertsioa
Impacto
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10.1128/jb.187.7.2348-2356.2005
Resumen
Staphylococcus epidermidis biofilm formation is associated with the production of the polysaccharide intercellular
adhesin (PIA)--poly-N-acetylglucosamine polysaccharide (PNAG) by the products of the icaADBC
operon. Recent evidence indicates that SarA, a central regulatory element that controls the production of
Staphylococcus aureus virulence factors, is essential for the synthesis of PIA/PNA ...
[++]
Staphylococcus epidermidis biofilm formation is associated with the production of the polysaccharide intercellular
adhesin (PIA)--poly-N-acetylglucosamine polysaccharide (PNAG) by the products of the icaADBC
operon. Recent evidence indicates that SarA, a central regulatory element that controls the production of
Staphylococcus aureus virulence factors, is essential for the synthesis of PIA/PNAG and the ensuing biofilm
development in this species. Based on the presence of a sarA homolog, we hypothesized that SarA could also
be involved in the regulation of the biofilm formation process in S. epidermidis. To investigate this, we
constructed nonpolar sarA deletions in two genetically unrelated S. epidermidis clinical strains, O-47 and
CH845. The SarA mutants were completely defective in biofilm formation, both in the steady-state conditions
of a microtiter dish assay and in the flow conditions of microfermentors. Reverse transcription-PCR experiments
showed that the mutation in the sarA gene resulted in downregulation of the icaADBC operon transcription
in an IcaR-independent manner. Purified SarA protein showed high-affinity binding to the icaA
promoter region by electrophoretic mobility shift assays. Consequently, mutation in sarA provoked a significant
decrease in the amount of PIA/PNAG on the cell surface. Furthermore, heterologous complementation of S.
aureus sarA mutants with the sarA gene of S. epidermidis completely restored biofilm formation. In summary,
SarA appeared to be a positive regulator of transcription of the ica locus, and in its absence, PIA/PNAG
production and biofilm formation were diminished. Additionally, we present experimental evidence showing
that SarA may be an important regulatory element that controls S. epidermidis virulence factors other than
biofilm formation. [--]
Materias
Staphylococcus epidermidis,
sarA,
PIA/PNAG,
Biofilm formation
Editor
American Society for Microbiology
Publicado en
Journal of Bacteriology, Apr. 2005, Vol. 187, No. 7, p. 2348–2356
Departamento
Universidad Pública de Navarra/Nafarroako Unibertsitate Publikoa. IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Versión del editor
Entidades Financiadoras
This work was supported by grant BIO2002-04542-C02-01 from the
Comisión Interministerial de Ciencia y Tecnología (C.I.C.Y.T.) and
grants from the Cardenal Herrera-CEU University, from the Conselleria
d’Agricultura, Pesca i Alimentació, and from the Generalitat
Valenciana (CTIDIA/2002/62) to J.R.P. A.L.C. acknowledges financial
support provided by the NIH (grant AI37142). Fellowship support for
María Ángeles Tormo from the Conselleria de Cultura, Educación y
Deporte and for Miguel Martí from the Conselleria d’Agricultura,
Pesca i Alimentació is gratefully acknowledged.