Histoplasma Requires SID1, a Member of an Iron-Regulated Siderophore Gene Cluster, for Host Colonization
A. Iron-dependent gene expression cluster from whole genome oligonucleotide microarray analysis of G217B yeast grown under iron replete (5 µM FeSO4) and iron limited (100 µM deferoxamine mesylate) conditions for 0, 4, 24, and 48 hours, as described in Materials and Methods. Red indicates up-regulated genes, green indicates down-regulated genes, black indicates genes that do not change in expression, and gray indicates that no data are available. Microarray time courses were repeated with three biological replicates. A representative experiment is shown. Similar results were seen for iron replete conditions of either 5 or 10 µM FeSO4. B. Quantitative RT-PCR of siderophore biosynthesis and utilization genes. Total RNA from the 0, 1, 4, and 24 hr time points used in the microarray analysis were analyzed for relative transcript levels using QRT-PCR. Transcript levels were normalized to ACT1 transcript. Relative quantities were normalized to t = 0 values (black bars). For the 1, 4, and 24 hr time points, white bars indicate growth in medium supplemented with FeSO4 (+Fe), and gray bars indicate growth in deferoxamine (+Df).