He T-profiler to identify the transcriptional factors that mediated the response to fusaricidin. The T-profiler is a computational tool that uses the t test to score changes in the average activity of predefined groups of genes based on the Gene Ontology categorization, upstream matches to a consensus transcription factor-binding motif, or the KEGG pathway [9]. In this study, the gene groups with significant t values (E = 0.05, TF model) are also presented in Table 2. Nine coregulated gene groups were found to be significantly perturbed by fusaricidin after 5 min, including SigW-, CcpA-, SigK-, SigE-, AbrB-, GerE-, FNR-, and SigB-regulated gene groups. As mentioned earlier, SigW probably activates a large stationaryphase regulon that functions in detoxification, production of antimicrobial compounds, or both. SigE and SigK regulate early and late mother cell-specific gene expression, respectively. AbrB is the regulon of transition state genes (negative regulation of abrB, aprE, ftsAZ, kinC, motAB, nprE, pbpE, rbs, spoOH, spoVG, tycA, sbo-alb, and yqxM-sipW-tasA, and positive regulation of comK and hpr). Eleven and 13 gene groups were significantly modulated after 20 and 170 min of treatment, respectively. The results showed a strong activation of genes in the SigB regulon after the fusaricidin treatment. SigB is a general stress-response regulator that controls at least 150 genes. Members of the 
SigB regulon are transientlyMechanisms of Fusaricidins to Bacillus subtilisFigure 6. The transport of cations. The 3 bars from left to right represent the fold changes of the gene expressions in response to the 3 time points (5, 20, and 170 min). The red bars represent an upregulation; the green bars, a downregulation; and the gray bars, the messages that did not significantly change relative to our cutoff 23977191 (3-fold increase in expression). doi:10.1371/journal.pone.0050003.ginduced after heat shock or salt, ethanol, or acid stress, or upon limitation of glucose and phosphate starvation. In our study, a significantly negative t value for SigB was observed, which revealed that the fusaricidin addition repressed the expression ofsome SigB regulon genes (Table 2). CcpA is a global regulator of carbon metabolism in B. subtilis and mediates carbon metabolite repression [21]. The t values of the genes of the CcpA-negative group indicated that these genes were significantly Solvent Yellow 14 biological activity overexpressedMechanisms of Fusaricidins to Bacillus subtilisFigure 7. The transport and oxidation stress response associated with Fe2+ and Mn2+. Fus, fusaricidin. doi:10.1371/journal.pone.0050003.gand that fusaricidin perturbs glucose metabolism. In B. subtilis, iron homeostasis is regulated by the ferric uptake regulator (Fur), which represses the expression of genes related to siderophore biosynthesis and iron uptake proteins. Iron limitation and oxidative stress are known to induce the Fur regulon [22]. The t values of the Furnegative genes showed that this gene group were Avasimibe biological activity overexpressed. The StrCon-negative genes are involved in energy production, and the negative t values associated with this group indicate that the associated genes are somewhat overexpressed.Effect of Fusaricidins on Cation TransportFusaricidins had detrimental effects on the cell membrane, which would engender a loss of intracellular ions. This would lead to the induction of genes involved in ion uptake to maintain cell osmotic pressure and intracellular steady state. We studied the cation transport of B. subtili.He T-profiler to identify the transcriptional factors that mediated the response to fusaricidin. The T-profiler is a computational tool that uses the t test to score changes in the average activity of predefined groups of genes based on the Gene Ontology categorization, upstream matches to a consensus transcription factor-binding motif, or the KEGG pathway [9]. In this study, the gene groups with significant t values (E = 0.05, TF model) are also presented in Table 2. Nine coregulated gene groups were found to be significantly perturbed by fusaricidin after 5 min, including SigW-, CcpA-, SigK-, SigE-, AbrB-, GerE-, FNR-, and SigB-regulated gene groups. As mentioned earlier, SigW probably activates a large stationaryphase regulon that functions in detoxification, production of antimicrobial compounds, or both. SigE and SigK regulate early and late mother cell-specific gene expression, respectively. AbrB is the regulon of transition state genes (negative regulation of abrB, aprE, ftsAZ, kinC, motAB, nprE, pbpE, rbs, spoOH, spoVG, tycA, sbo-alb, and yqxM-sipW-tasA, and positive regulation of comK and hpr). Eleven and 13 gene groups were significantly modulated after 20 and 170 min of treatment, respectively. The results showed a strong activation of genes in the SigB regulon after the fusaricidin treatment. SigB is a general stress-response regulator that controls at least 150 genes. Members of the SigB regulon are transientlyMechanisms of Fusaricidins to Bacillus subtilisFigure 6. The transport of cations. The 3 bars from left to right represent the fold changes of the gene expressions in response to the 3 time points (5, 20, and 170 min). The red bars represent an upregulation; the green bars, a downregulation; and the gray bars, the messages that did not significantly change relative to our cutoff 23977191 (3-fold increase in expression). doi:10.1371/journal.pone.0050003.ginduced after heat shock or salt, ethanol, or acid stress, or upon limitation of glucose and phosphate starvation. In our study, a significantly negative t value for SigB was observed, which revealed that the fusaricidin addition repressed the expression ofsome SigB regulon genes (Table 2). CcpA is a global regulator of carbon metabolism in B. subtilis and mediates carbon metabolite repression [21]. The t values of the genes of the CcpA-negative group indicated that these genes were significantly overexpressedMechanisms of Fusaricidins to Bacillus subtilisFigure 7. The transport and oxidation stress response associated with Fe2+ and Mn2+. Fus, fusaricidin. doi:10.1371/journal.pone.0050003.gand that fusaricidin perturbs glucose metabolism. In B. subtilis, iron homeostasis is regulated by the ferric uptake regulator (Fur), which represses the expression of genes related to siderophore biosynthesis and iron uptake proteins. Iron limitation and oxidative 
stress are known to induce the Fur regulon [22]. The t values of the Furnegative genes showed that this gene group were overexpressed. The StrCon-negative genes are involved in energy production, and the negative t values associated with this group indicate that the associated genes are somewhat overexpressed.Effect of Fusaricidins on Cation TransportFusaricidins had detrimental effects on the cell membrane, which would engender a loss of intracellular ions. This would lead to the induction of genes involved in ion uptake to maintain cell osmotic pressure and intracellular steady state. We studied the cation transport of B. subtili.
