Comparative proteome analysis of Staphylococcus aureus biofilm and planktonic cells and correlation with transcriptome profiling

Abstract

Pathogenic staphylococci can form biofilms in which they show a higher resistance to antibiotics and the immune defense system than their planktonic counterparts, which suggests that the cells in a biofilm have an altered metabolic activity. Here, 2-D PAGE was used to identify secreted, cell wall-associated and cytoplasmic proteins expressed in Staphylococcus aureus after 8 and 48 h of growth. The proteins were separated at pH ranges of 4-7 or 6-11. The protein patterns revealed significant differences in 427 protein spots; from these, 258 non-redundant proteins were identified using ESI-MS/MS. Biofilm cells expressed higher levels of proteins associated with cell attachment and peptidoglycan synthesis, and in particular fibrinogen-binding proteins. Enzymes involved in pyruvate and formate metabolism were upregulated. Furthermore, biofilm cells expressed more staphylococcal accessory regulator A protein (SarA), which corroborates the positive effect of SarA on the expression of the intercellular adhesion operon ica and biofilm growth. In contrast, proteins, such as proteases and particularly immunodominant antigen A (IsaA) and staphylococcal secretory antigen (SsaA), were found in lower amounts. The RNA expression profiling largely supports the proteomic data. The results were mapped onto KEGG pathways.

Staphylococcal Biofilms

“…Three transcriptional profiling-based manuscripts have been published, two on S. aureus (Beenken et al 2004;Resch et al 2005) and one on S. epidermidis (Yao et al 2005), and in addition, proteomics were used to confirm results obtained by the microarray experiments (Resch et al 2006). The general lessons learned from these studies are comparable although differences exist that originate most likely from different experimental setups.…”

“…The general lessons learned from these studies are comparable although differences exist that originate most likely from different experimental setups. In addition, it has to be taken into consideration that two studies (Resch et al 2005;Resch et al 2006) were performed in the SA113 strain of S. aureus, which is a natural agr mutant.…”

Proteome approaches combined with Fourier transform infrared spectroscopy revealed a distinctive biofilm physiology in Bordetella pertussis

“…Previous studies have focused on comparing physiological features between biofilm and planktonic populations for different bacteria [9,14,33,34]; however, none of these studies have addressed this question by combining proteomic and FT-IR spectroscopy techniques.…”

Staphylococcus aureus Biofilm Metabolism and the Influence of Arginine on Polysaccharide Intercellular Adhesin Synthesis, Biofilm Formation, and Pathogenesis

“…This is an advantageous adaptation allowing bacteria to acquire necessary amino acids from their environment and redirect energy from amino acid biosynthesis into growth. It has been postulated that amino acid catabolism is important for staphylococcal biofilm formation and pH homeostasis (2,44,45). To determine which amino acids S. aureus extracted from the culture medium during biofilm growth, we measured the free amino acid concentrations of culture medium effluent and expressed this as a function of the free amino acid concentration in sterile culture medium ( Fig.…”

“…Due to the importance of S. aureus biofilms in medical device-associated infections, a considerable amount of research has been directed at understanding the mechanisms of biofilm formation. Much of this research has focused on the bacterial mediators of biofilm formation (41,43,56,59), the environmental effectors of biofilm formation (26,28,50), and, more recently, the global changes that occur during biofilm development (2,44,45,60). The consensus from transcriptional profiling studies of S. aureus biofilms is that bacteria are growing microaerobically or anaerobically relative to planktonic cultures (2,45).…”