Search

Insertion of an 18-amino-acid-encoding sequence within the fpvA gene revealed permissive sites at residues Y350, A402, R451, R521 and R558, consistent with these residues occurring in extramembranous loop regions of the protein. Insertions of R451, R521 and R558 did not have negative effects on receptor function, even though insertions at Y350 and A402 affected ferric pyoverdine binding and uptake. The latter region may participate or interact with the ligand-binding site.

The participation of multidrug efflux systems of Pseudomonas aeruginosa in organic solvent tolerance was investigated using genetically defined efflux pump mutants. The findings demonstrated that the three efflux systems, namely MexE-MexF-OprN, MexC-MexD-OprJ and MexA-MexB-OprM, induce tolerance for such organic solvents as p-xylene and n-hexane. The expression of MexAB-OprM was associated with the maximum tolerance level and was a factor in the intrinsic solvent tolerance of the microorganism.

Research was conducted to test whether the outer membrane OprM protein influences beta-lactam recognition and efflux in Pseudomonas aeruginosa. The oprM gene was cloned on a SphI fragment into a derivative called pXZL01 while the MexCD-OprM efflux system was constructed and analyzed for reconstitution of efflux activity. Results showed that the efflux components are highly homologous and are characterized by an integral cytoplasmic membrane component, a linker protein and an outer membrane protein.

The PfeR (regulator) of Pseudomonas aeruginosa controls ferric enterobacter receptor protein (pfeA) expression by binding to the pfeA promoter. The enterobactin-dependent binding of PfeR with the pfeA promoter is mediated by PfeS (sensor). The chromosomal pfeS is expressed by bacterial cells under iron-limiting conditions to activate PfeR and enhance its binding to the pfeA promoter. Two pairs of direct repeats are present in the region that is necessary for the expression of pfeA.

The Pseudomonas aeruginosa tonB gene encodes a 36,860 Da protein that is rich in Pro residues with Glu-Pro/Lys-Pro repeats. The P. aeruginosa TonB protein, TonB(sub P.a.) has no N-terminal membrane anchor sequence unlike other TonB proteins. An internal N-terminal signal/anchor sequence is, however, present. P. aeruginosa tonB derivatives lack siderophore-mediated iron acquisition and low iron supplies induce tonB expression. TonB(sub P.a.) is more similar to the Escherichia coli TonB protein than the P. putida protein.

The expression of a plasmid containing the Pseudomonas aeruginosa PAO 15.1 kb chromosomal fragment or its 10.8 kb derivative restores the wild-type yellow-green phenotype to P. aeruginosa pyoverdine-deficient (pvd) mutants. The 10.8 kb fragment is composed of the 66-70 min area of the PAO chromosome and contains genes involved in the synthesis of the pyoverdine chromophore. The pvd mutants produce pseudoverdine that is similar to pyoverdine, but is unable to stimulate the growth of pvd mutants in the presence of iron chelators or to control iron uptake.

The regulatory protein PchR acts as both an activator and a repressor of the ferripyochelin receptor gene (fptA) and also the pchR expression in Pseudomonas aeruginosa. Deactivation of the pchR gene by an omega-Hg cartridge decreases the expression of fptA. The gene suppresses the activity of the fptA-lacZ fusion gene in Escherichia coli. However, the deactivation of pchR in a mutant lacking pyochelin restores the fptA expression. This indicates that PchR suppresses its own expression.

Legislatures often make important economic decisions. A decade ago economists viewed each legislator as the agent, if not of the median voter, of some pivotal voter in a party constituency. Therefore, the voting decision of a legislator could readily be predicted if one could measure the preferences of the relevant pivotal voter. Models where interests on specific issues can be simply linked to votes on the same issues are questionable, however, since votes will be traded across issues. Political parties are one important vehicle for organizing such trades. A simple empirical test for the United States Senate, however, clearly rejects the notion that the representative is the agent of the median voter or a local party constituency, even if vote trades are allowed. Thus, there is ample opportunity for politicians, even under reelection constraints, to either voice their own ideology or that of idiosyncratic support coalitions. The relevant theory and empirical evidence is summarized, and some validating tests for European parliaments are suggested. Keywords: Legislatures; Agent of constituent; Ideologue; NOMINATE procedure

Pseudomonas aeruginosa becomes multiple antibiotic resistant due to the presence of the 50 kilodalton outer membrane protein (ORFC)-determined drug efflux, ORFA-ORFB-ORFC (oprK). Dipyridyl, streptonigrin, ciprofloxacin, chloramphenicol and tetracycline affect mutants defective in ORFC, ORFB and ORFA. The presence of OprK yields several antimicrobial agents with more resistance.

A gene (pchR) concerned with the regulation of the production of the 75-kDa ferripyochelin receptor protein and pyochelin in Pseudomonas aeruginosa K372, which is deficient in the two substances, was determined and characterized. The involvement of PchR, the iron-regulated stimulation of pyochelin and ferripyochelin receptor synthesis are confirmed because PchR demonstrates homology to the AraC transcriptional activation protein of enteric bacteria.

The gene encoding the ferripyoverdine receptor of Pseudomonas aeruginosa PAO was cloned and the nucleotide sequence studied. The receptor was found to be homologous to the ferric pseudobactin receptor PupA of Pseudomonas putida. The cloning process was done by using the phagemid-based in vivo cloning system because the P. aeruginosa KA37 lacks the ferripyoverdine receptor. The fpvA protein is predicted to comprise 797 amino acids based on the assumption that the second methionine identified in the fpvA open reading frame is initiated by the protein.

Complementation analysis identified a 3.2-kb Pseudomonas aeruginosa DNA fragment as encoding the 80-kDa high-affinity ferric enterobactin receptor protein. Sequence analysis showed that the P. aeruginosa receptor protein, designated PfeA, is analogous to the Escherichia coli receptor protein, FepA. In addition, PfeA could function well in place of FepA within the E. coli system, suggesting that P. aeruginosa possesses analogous uptake components as that in E. coli.

Research has been conducted on Pseudomonas aeruginosa. The ability of p yoverdine to control FpvA production in P. aeruginosa has been investigated, and the details are presented.