genomewide characterization of host-pathogen interactions by ...

Maren Depke
Results
Pathogen Gene Expression Profiling
Table R.5.7: Expression of genes known to be regulated by SaeRS (according to Rogasch et al. 2006), which exhibited differential
expression in internalized S. aureus RN1HG in S9 cells.
LocusTag gene annotation
fold change in comparison to
baseline 1 h serum/CO 2 control
2.5 h
internalized a
6.5 h
internalized a
SAOUHSC_01942 splA serine protease SplA 3.2 30.4
SAOUHSC_01939 splC serine protease SplC 4.8 43.1
SAOUHSC_02803 fnbA fibronectin-binding protein precursor, putative 6.2 6.4
SAOUHSC_02802 fnbB fibronectin binding protein B, putative 7.0 3.1
SAOUHSC_02709 hlgC leukocidin s subunit precursor, putative 5.3 17.9
SAOUHSC_02708 gamma-hemolysin h-gamma-ii subunit, putative 9.6 19.4
SAOUHSC_00196 fadB hypothetical protein SAOUHSC_00196 84.4 16.6
SAOUHSC_00232 lrgA antiholin-like protein lrgA 4.0 5.3
SAOUHSC_01921 hypothetical protein SAOUHSC_01921 4.8 2.2
SAOUHSC_02710 hlgB leukocidin f subunit precursor 3.4 13.4
SAOUHSC_01121 hla alpha-hemolysin precursor 1.9 3.2
SAOUHSC_02169 chp chemotaxis inhibitory protein 1.7 4.4
SAOUHSC_02161 eap MHC class II analog protein 1.8 11.0
SAOUHSC_01114 efb fibrinogen-binding protein 1.9 2.7
SAOUHSC_00816 emp extracellular matrix and plasma binding protein, putative -1.4 2.9
SAOUHSC_00715 saeR response regulator, putative -1.2 2.1
SAOUHSC_01115 hypothetical protein SAOUHSC_01115 1.8 3.0
SAOUHSC_00354 hypothetical protein SAOUHSC_00354 -1.7 2.9
SAOUHSC_00192 coa coagulase 6.3 1.8
SAOUHSC_00400 hypothetical protein SAOUHSC_00400 9.1 1.7
SAOUHSC_00399 hypothetical protein SAOUHSC_00399 10.4 1.9
SAOUHSC_00818 nuc thermonuclease precursor -4.4 1.2
SAOUHSC_02229 anti repressor 1.4 -2.9
SAOUHSC_00182 hypothetical protein SAOUHSC_00182 -2.6 -2.8
a Differentially regulated genes (significant with p* < 0.05 and with a minimal absolute fold change of 2) are indicated in bold.
Differential expression of virulence associated genes
Very important for colonization of the host, but also for internalization into host cells are the
staphylococcal membrane bound adhesins, MSCRAMMs. Genes coding for fibrinogen binding
protein A and B (fnbA, fnbB) and for clumping factor A and B (clfA, clfB) were induced in
internalized staphylococci 2.5 h after start of infection. Differential expression of fnbA and clfA
was still detectable at the 6.5 h time point whereas that of fnbB and clfB was not significant
anymore, although a trend of induction was visible according to the fold change values. The
control samples exhibited only less consistent expression changes. An exception might be the
expression of fnbA and clfA in the 6.5 h serum/CO 2 control. Here, a trend of induction was visible,
but the difference could not be determined statistically because of the number of replicates
(Fig. R.5.14 A, B). Soluble adhesins bind to host structures. They can mediate bacterial cell
attachment indirectly by involving linker molecules. Some alternatively exist in cell-surface
associated forms. IsaB has an intermediate position as membrane bound and secreted protein,
which was recently discovered to bind extracellular dsDNA and which is implicated in virulence,
but whose exact function is still not identified (Mackey-Lawrence et al. 2009). In staphylococci
internalized by S9 cells, expression of isaB, eap, coa, vwb, emp, and efb was induced in at least
one of the two analyzed time points of internalization. In this group, the repression of coa and
vwb occurred in the 2.5 h serum/CO 2 and 2.5 h anaerobic control samples, and vwb and efb were
significantly less expressed in the exponential growth samples with which inoculation of S9 cell
culture plates took place. Contrarily, the gene eap was two-fold induced in the 2.5 h serum/CO 2
controls, and isaB showed induction in anaerobiosis (Fig. R.5.14 A, B, C).
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