posted on 2015-09-04, 00:00authored byMartin Moche, Rabea Schlüter, Jörg Bernhardt, Kristina Plate, Katharina Riedel, Michael Hecker, Dörte Becher
Staphylococcal
biofilms are associated with persistent infections
due to their capacity to protect bacteria against the host’s
immune system and antibiotics. Cell-surface-associated proteins are
of great importance during biofilm formation. In the present study,
an optimized biotinylation approach for quantitative GeLC–MS-based
analysis of the staphylococcal cell-surface proteome was applied and
the cytoplasmic protein fraction was analyzed to elucidate proteomic
differences between colony biofilms and planktonic cells. The experimental
setup enabled a time-resolved monitoring of the proteome under both
culture conditions and the comparison of biofilm cells to planktonic
cells at several time points. This allowed discrimination of differences
attributed to delayed growth phases from responses provoked by biofilm
conditions. Biofilm cells expressed CcpA-dependent catabolic proteins
earlier than planktonic cells and strongly accumulated proteins that
belong to the SigB stress regulon. The amount of the cell-surface
protein and virulence gene regulator Rot decreased within biofilms
and MgrA-dependent regulations appeared more pronounced. Biofilm cells
simultaneously up-regulated activators (e.g., SarZ) as well as repressors
(e.g., SarX) of RNAIII. A decreased amount of high-affinity iron uptake
systems and an increased amount of the iron-storage protein FtnA possibly
indicated a lower demand of iron in biofilms.