1.6 Å Crystal structure of a PA2721 protein from <i>pseudomonas aeruginosa</i>—A potential drug‐resistance protein

Nocek, B.; Cuff, M.E.; Evdokimova, E.; Edwards, A.M.; Joachimiak, Andrzej; Savchenko, Alexei

doi:10.1002/prot.20659

Cited by 2 publications

(1 citation statement)

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“…In this respect, it is interesting to note that the genome of the well-studied phenazine producer Pseudomonas aeruginosa encodes over 20 proteins of this family. The structures of four of these proteins have been determined, but with the exception of fosfomycin resistance protein PA1129 (PDB entry 1NNR ) [ 23 ], their functions have not been investigated experimentally ( P. aeruginosa genes PA1353, PA1358 and PA2721 with PDB entries 1U6L , 1U7I and 1U69 [ 24 ], all deposited by structural genomics centers). However, since some of these uncharacterized proteins possess the two aromatic residues required for the π-stacking sandwich binding of aromatic ligands (Figure 4C ), they may be capable of binding phenazines and other related aromatic compounds.…”

Section: Discussionmentioning

confidence: 99%

Atomic resolution structure of EhpR: phenazine resistance in Enterobacter agglomerans Eh1087 follows principles of bleomycin/mitomycin C resistance in other bacteria

et al. 2011

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BackgroundThe phenazines are redox-active secondary metabolites that a large number of bacterial strains produce and excrete into the environment. They possess antibiotic activity owing to the fact that they can reduce molecular oxygen to toxic reactive oxygen species. In order to take advantage of this activity, phenazine producers need to protect themselves against phenazine toxicity. Whereas it is believed that phenazine-producing pseudomonads possess highly active superoxide dismutases and catalases, it has recently been found that the plant-colonizing bacterium Enterobacter agglomerans expresses a small gene ehpR to render itself resistant towards D-alanyl-griseoluteic acid, the phenazine antibiotic produced by this strain.ResultsTo understand the resistance mechanism installed by EhpR we have determined its crystal structure in the apo form at 2.15 Å resolution and in complex with griseoluteic acid at 1.01 Å, respectively. While EhpR shares a common fold with glyoxalase-I/bleomycin resistance proteins, the ligand binding site does not contain residues that some related proteins employ to chemically alter their substrates. Binding of the antibiotic is mediated by π-stacking interactions of the aromatic moiety with the side chains of aromatic amino acids and by a few polar interactions. The dissociation constant KD between EhpR and griseoluteic acid was quantified as 244 ± 45 μM by microscale thermophoresis measurements.ConclusionsThe data accumulated here suggest that EhpR confers resistance by binding D-alanyl-griseoluteic acid and acting as a chaperone involved in exporting the antibiotic rather than by altering it chemically. It is tempting to speculate that EhpR acts in concert with EhpJ, a transport protein of the major facilitator superfamily that is also encoded in the phenazine biosynthesis operon of E. agglomerans. The low affinity of EhpR for griseoluteic acid may be required for its physiological function.

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Section: Discussionmentioning

confidence: 99%