The Staphylococcus aureus secretome - TI Pharma

Mapping the pathways to staphylococcal pathogenesis by comparative secretomics
Figure 3. Dynamics of the amount of extracellular proteins during growth of S. aureus RN6390 in TSB
medium
(A) Individual dual channel 2D patterns of extracellular proteins during the different phases of the growth curve
of cells grown in TSB medium were assembled into a movie. The protein pattern at an OD 540 of 1 (labelled in
green) was compared with the protein pattern at the respective higher optical densities (labelled in red). As a
consequence of the dual channel labelling, spots of which the intensities do not differ in the compared gels will be
yellow; spots of different intensities will be either green or red (Bernhardt et al., 1999). (B) Growth curve of S.
aureus RN6390 grown in TSB medium as determined by OD 540 readings. The sampling points for proteomics
analyses are indicated by arrows. (C) Proteomic signatures of selected proteins representing different regulatory
groups as revealed by dual channel imaging. The relative amounts of the respective proteins at an OD 540 of 1
(spots labelled in green) of cells grown in TSB medium were compared with the relative amounts of these proteins
at higher optical densities (spots labelled in red). Proteins were stained with Sypro Ruby ® .
Exported staphylococcal virulence factors
S. aureus and S. epidermidis are organisms that occur naturally in and on the human body.
While S. epidermidis is mostly present on the human skin, S. aureus can be found on mucosal
surfaces. S. aureus is carried by 30-40% of the population (Peacock et al., 2001) and can
readily be identified in the nose, but the organism can also be detected in other moist regions
of the human body, such as axilla, perineum, vagina and rectum, thereby forming a major
reservoir for infections. Although most staphylococcal infections are nosocomial (i.e.
hospital-acquired), an increase in the number of cases of community-acquired antibiotic
(methicillin) resistant infections is currently observed world-wide (Centers for Disease
Control and Prevention, 2003; Grundmann et al., 2002; Vandenesch et al., 2003). The risk of
intravascular and systemic infection by S. aureus rises when the epithelial barrier is disrupted
by intravascular catheters, implants, mucosal damage or trauma. Interestingly, after infection,
19