2V4D

Re-refinement of MexA adaptor protein

Summary for 2V4D

• Entry DOI: 10.2210/pdb2v4d/pdb
• Related: 1T5E 1VF7
• Descriptor: MULTIDRUG RESISTANCE PROTEIN MEXA, SULFATE ION (2 entities in total)
• Functional Keywords: membrane protein, transport protein, cell inner membrane, mexa, membrane, palmitate, transport, lipoprotein, antibiotic resistance, antibiotic efflux pump, coiled coil, cell membrane, inner membrane, periplasmic adaptor protein
• Biological source: PSEUDOMONAS AERUGINOSA
• Cellular location: Cell inner membrane; Lipid-anchor: P52477
• Total number of polymer chains: 13
• Total formula weight: 503563.84

Authors

Symmons, M.F.,Bokma, E.,Koronakis, E.,Hughes, C.,Koronakis, V. (deposition date: 2008-09-18, release date: 2009-04-14, Last modification date: 2023-12-13)

Primary citation

Symmons, M.F.,Bokma, E.,Koronakis, E.,Hughes, C.,Koronakis, V.
The Assembled Structure of a Complete Tripartite Bacterial Multidrug Efflux Pump.
Proc.Natl.Acad.Sci.USA, 106:7173-, 2009

PubMed Abstract: Bacteria like Escherichia coli and Pseudomonas aeruginosa expel drugs via tripartite multidrug efflux pumps spanning both inner and outer membranes and the intervening periplasm. In these pumps a periplasmic adaptor protein connects a substrate-binding inner membrane transporter to an outer membrane-anchored TolC-type exit duct. High-resolution structures of all 3 components are available, but a pump model has been precluded by the incomplete adaptor structure, because of the apparent disorder of its N and C termini. We reveal that the adaptor termini assemble a beta-roll structure forming the final domain adjacent to the inner membrane. The completed structure enabled in vivo cross-linking to map intermolecular contacts between the adaptor AcrA and the transporter AcrB, defining a periplasmic interface between several transporter subdomains and the contiguous beta-roll, beta-barrel, and lipoyl domains of the adaptor. With short and long cross-links expressed as distance restraints, the flexible linear topology of the adaptor allowed a multidomain docking approach to model the transporter-adaptor complex, revealing that the adaptor docks to a transporter region of comparative stability distinct from those key to the proposed rotatory pump mechanism, putative drug-binding pockets, and the binding site of inhibitory DARPins. Finally, we combined this docking with our previous resolution of the AcrA hairpin-TolC interaction to develop a model of the assembled tripartite complex, satisfying all of the experimentally-derived distance constraints. This AcrA(3)-AcrB(3)-TolC(3) model presents a 610,000-Da, 270-A-long efflux pump crossing the entire bacterial cell envelope.

PubMed: 19342493
DOI: 10.1073/PNAS.0900693106

Experimental method

X-RAY DIFFRACTION (3.2 Å)