PMID:11858709
| Citation |
Avila-Sakar, AJ, Misaghi, S, Wilson-Kubalek, EM, Downing, KH, Zgurskaya, H, Nikaido, H and Nogales, E (2001) Lipid-layer crystallization and preliminary three-dimensional structural analysis of AcrA, the periplasmic component of a bacterial multidrug efflux pump. J. Struct. Biol. 136:81-8 |
|---|---|
| Abstract |
The multidrug efflux complex AcrAB-TolC confers intrinsic drug resistance in Escherichia coli by pumping antibiotics out of the cell. We determined a low-resolution (20 A) structure of AcrA, the periplasmic component, by electron crystallography. Expressed with a His-tag at its carboxyl-terminus, the protein bound to lipid layers containing the nickel-chelating phospholipid DOGS-NTA. Under the lipid layers, AcrA crystallized in layer group P2(1)22, with a unit cell size of 157 by 95 A and a thickness of about 100 A. The four asymmetric units in the unit cell are organized into what appears to be two rings, each with a central opening of 30 A in diameter. Within each ring, the density can be interpreted as following a pseudo-helical path, approximately 210 A long. This length matches that of monomeric AcrA in solution, previously estimated by light scattering and hydrodynamic measurements. On one side the density has a tubular shape, with a thickness of about 25 A, while on the other side the densities of the upper and lower parts of the pseudo-helical path are fused into a shield. |
| Links |
PubMed Online version:10.1006/jsbi.2001.4418 |
| Keywords |
Bacterial Proteins/chemistry; Carrier Proteins; Crystallography/methods; Escherichia coli/metabolism; Escherichia coli Proteins; Fourier Analysis; Lipoproteins/chemistry; Membrane Proteins/chemistry; Membrane Transport Proteins; Microscopy, Electron/methods; Models, Molecular; Multidrug Resistance-Associated Proteins; Periplasm/chemistry |
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