Preliminary crystallographic analysis of the antibiotic discharge outer membrane lipoprotein OprM ofPseudomonas aeruginosawith an exceptionally long unit cell and complex lattice structure

Abstract

Crystals of the drug-discharge outer membrane protein OprM (MW = 50.9 kDa) of the MexAB-OprM multidrug transporter of Pseudomonas aeruginosa have been grown at 293 K in the presence of 2-methyl-2,4-propanediol and a combination of surfactants. The crystal belonged to space group R32, with unitcell parameters a = b = 85.43, c = 1044.3 A Ê. Diffraction data for OprM were obtained using the undulator synchrotron-radiation beamline at SPring-8 (BL44XU, Osaka University), which allowed an extra-long specimen-todetector distance with a wide detector area. The crystal diffracted to 2.56 A Ê resolution using 0.9 A Ê X-rays from the synchrotron-radiation source. A heavyatom derivative for isomorphous replacement phasing was obtained using iridium chloride. crystallization communications Acta Cryst. (2005). F61, 131±133 Akama et al. OprM 133 Figure 2 Difference Patterson map in the Harker plane. (a) shows the isomorphous difference map and (b) the Bijvoet anomalous difference map. Both peaks are from atomic vector site A (x, y, z) = (0.0645, 0.4028, 0.3220). The maps were contoured at intervals of 1.0 times the r.m.s. density of the map.

Untitled

“…Drug extrusion lowers the antimicrobial's intracellular concentration, allowing the bacterium to survive in environments with high antimicrobial concentrations. Both gram-positive and gram-negative bacteria contain multidrug resistance efflux pumps, which can be chromosomally or plasmid-encoded proteins 17 . Since, these proteins are naturally present in bacteria, the persistent presence of the substrate causes their over-expression 18 , which results in the development of the acquired resistance.…”