Bioinformatic analysis predicts that the amino termini of both proteins are also cytoplasmic. Thus, like E. coli AmpG, both the amino and carboxyl termini would be cytoplasmic [15] (Figure 4). Consistent with a role in transport, AmpP has an MFS domain [23, 30]. The Major Facilitator Superfamily domain is present in approximately one-fourth of all known prokaryotic transport proteins [34]. Interestingly, most MFS proteins have 12 TM domains, while AmpP, like E. coli AmpG, has only 10 [35]. The topology analysis suggests PAO1 AmpG has 14 TM domains. PAO1 AmpG also has an insignificant MFS1 domain. A few MFS proteins have also been shown to have 14 TM domains [29,

35]. The ampG and ampP genes are essential for maximum β-lactamase induction Because of the similarity between AmpG from Enterobacteriaceae and PAO1 AmpG and AmpP, β-lactamase levels of single ampG and ampP mutant isogenic strains were determined. Although an increase in β-lactamase ABT-263 nmr activity was observed, JPH203 order neither

the ampG nor ampP mutant strain produced the same level of β-lactamase in the presence of benzyl-penicillin as PAO1 (Table 1, Figure 5). Moreover, inactivation of ampG or ampP abolishes induction of P amp C (Figure 6). This indicates that both ampG and ampP are essential for chromosomal β-lactamase induction. These genes did not cross-complement or exhibit gene dosage effects indicating that they play different roles in the induction pathway (Table 1). These results are consistent with recent data demonstrating that mutation of ampG affects induction of β-lactamase and failure of ampP to complement an ampG mutation [28]. Furthermore, the analysis

using increasing benzyl-penicillin concentrations, shows that ampP plays an important role at lower inducer concentrations, whereas ampG is crucial at higher concentrations (Figure 5). Mutation of ampG affects PAO1 β-lactam resistance (Table 2) [28]. Recent studies by Zhang et al., in which deletion of ampG results in increased sensitivity to ampicillin [28], are consistent with results presented here (Table 2). In addition, ampG inactivation increases imipenem sensitivity (Table 2). Loss of ampP (also referred to as ampGh1) function did not affect β-lactam sensitivity in either study Cytidine deaminase (Table 2) [28]. AmpP (PA4218) has previously been named FptX due to its homology to RhtX in Sinorhizobium meliloti 2011 [36]. PA4219 does not have a S. meliloti orthologue [36]. Mutation of ampP in a P. aeruginosa CDC5 derivative that produces pyochelin but not pyoverdine, resulted in loss of pyochelin utilization [36]. In agreement with a role in pyochelin utilization, ampP is located next to genes PLK inhibitor involved in pyochelin biosynthesis and transport [23, 36]. Thus, the results presented in Table 1 and Figures 5 and 6 demonstrate that ampP is involved in β-lactamase induction in addition to its previously characterized role in pyochelin utilization [36].