Transcriptional control of resistance to Mn(II) and Cu(II). (I.) SirR is a Mn(II)-dependent repressor of the Mn-uptake ABC transport system genes—zurA, zurM, and ycdh. (A) Effect of Mn(II) on survival of the ΔsirR strain relative to the parent Δura3 strain. Growth was measured as increase in cell density (OD600) after culturing for 27 h at 37°C in the presence of increasing concentrations of Mn(II). (B) Ninety differences in transcriptional responses to Mn(II) in the ΔsirR strain relative to the parent Δura3 strain were determined using the SAM algorithm (Tusher et al. 2001) (Supplemental Fig. 6), normalized (variance = 1; mean = 0) and hierarchical clustered (Euclidean distance/Average Linkage). (C) Normalized log10 ratios of mRNA level changes for zurA, zurM, ycdH, (identified in group I in the two hierarchical clusters in B in the absence and presence of Mn(II) in Δura3 and ΔsirR strain backgrounds. Transcript levels for these ABC transporter subunits are down-regulated in the presence of SirR and Mn(II). (II.) VNG1179C is a Cu(II)-dependent activator of the Cu(II)-efflux ATPase YvgX. (A) Effect of Cu(II) on survival of ΔVNG1179C strain relative to the parent Δura3 strain. Survival was measured as described above, but with increasing doses of Cu(II) instead of Mn(II). (B) A total of 139 differences in transcriptional response to Cu(II) in the ΔVNG1179C strain relative to the parent Δura3 strain were filtered, normalized, and clustered as described in B (SF2). (C) yvgX was identified among genes in group II of the two main hierarchical clusters. Raw log10 ratios of mRNA level changes for yvgX in the absence and presence of Cu(II) in the Δura3 and ΔVNG1179C strain backgrounds indicate that it is up-regulated only in the presence of both Cu(II) and VNG1179C.
