Hfq, SmpB Targets in Salmonella Figure 4. Measurement of protein levels of pdu genes in DsmpB and Dhfq strains grown under LB Stat and acidic minimal media conditions. Heatmap showing 134 Pdu peptides that represent 11 individual Pdu proteins up-regulated under acidic minimal media (AMM-2) growth condition (Panel A) and 124 Pdu peptides that represent 11 individual Pdu proteins up-regulated under LB Stat growth condition (Panel D) in Dhfq and DsmpB strains relative to wild-type. Salmonella strains harboring HA-tag at each Pdu gene were grown in acidic minimal media (AMM-2) (Panel B and C) and under LB stat phase (Panel E and F) as described. Same amount of cell lysates was loaded in each lane and probed by Western blot analysis for the Pdu-encoded proteins and a control protein DnaK. The level of Pdu-encoded protein expressed in each strain was normalized to the DnaK level. Intracellular DnaK level in each lane was set to 100%. doi:10.1371/journal.pone.0004809.g004 Figure 5. Transcripts of pdu genes remain unchanged in DsmpB and Dhfq strains. Total RNA was isolated from Salmonella cells grown under acidic minimal media (AMM-2) growth condition (Panel A) or LB Stat growth condition (Panel B) and mRNA level of pdu genes was quantified via RT- PCR using gyrB mRNA level for normalization. As controls the mRNA level of smpB and hfq genes were also quantified in a similar fashion. Expression ratios (smpB or hfq/14028s) were averaged from three individual experiments and shown on a logarithmic scale. doi:10.1371/journal.pone.0004809.g005 PLoS ONE | www.plosone.org 7 March 2009 | Volume 4 | Issue 3 | e4809