The loss of up to 29 bp from the 3′ end (Probes IV, V, and VI) had no effect on Vfr selleck screening library binding (Figure 7D and E). However, the loss of 6 additional bp from probe VI, which deleted the consensus Vfr binding site completely, eliminated Vfr binding (Probe VII) (Figure 7E). Therefore, we localized Vfr binding within the upstream region of PA2782-mep72 to a 33-bp region that carries only 6 bp of the consensus Vfr binding sequence (Figure 7E). These results suggest that, unlike other Vfr-regulated genes, Vfr binding to the PA2782-mep72 upstream

region does not require the known Vfr consensus sequence. CYT387 datasheet Discussion Experiments described in this study indicate that the P. aeruginosa gene PA2783 encodes a secreted endopeptidase, which we have named Mep72. The predicted protein, which has a typical leader peptide at its amino terminus, selleck inhibitor belongs to the M72 family of metallopeptidases [39]. According to the MEROPS Peptidase Database, the P. aeruginosa Mep72 is a member of the peptidyl-Asp metallopeptidases (M72.001), proteins that degrade aspartate containing substrates by cleaving peptide bonds at the amino side of aspartate or cysteic acid [45]. Additional experiments would be needed to confirm such an activity. P. aeruginosa produces

at least three well characterized extracellular proteases/peptidases, LasB, LasA, and PrpL. LasB is a metalloendopeptidase that belongs to the thermolysin (M4) family [39], LasA is a 20-kDa zinc metalloendopeptidase that belongs to the β-lytic endopeptidase family (M23) [39, 46], and PrpL is a 27-kDa endopeptidase belonging to the serine endopeptidase family L-NAME HCl [39, 47, 48]. Compared with these extracellular proteases, Mep72 has several notable characteristics. First, it is less efficient in proteolytic activity. Neither the loss of the functional gene in P. aeruginosa nor the presence of multiple copies of mep72 (pAB2) in PAO1 or PAO-R1 enhanced the proteolytic activity (data not shown). Second, similar to LasB, LasA, PrpL, and other P. aeruginosa proteases, Mep72 is likely to be secreted to the extracellular

environment. The lack of transmembrane regions within the predicted protein further supports this suggestion (data not shown). The presence of LasB and other proteases within the PAO1 supernatant prevented us from detecting Mep72 proteolytic activity (data not shown). We were fortunate to detect strong extracellular proteolytic activity in E. coli DH5α carrying a mep72 plasmid (Figure 6A). However, similar to other P. aeruginosa proteins, when we overexpressed mep72 from the pBAD inducible promoter, Mep72 was trapped within the E. coli membranes (probably in inclusion bodies) (Figure 6C, D). We plan to produce polyclonal antibodies to the recombinant Mep72 encoded by pAB4 and utilize the antibodies to detect Mep72 within the supernatant of PAO1.