3T51: Crystal Structures Of The Pre-Extrusion And Extrusion States Of The Cusba Adaptor-Transporter Complex

Gram-negative bacteria expel various toxic chemicals via tripartite efflux pumps belonging to the resistance-nodulation-cell division superfamily. These pumps span both the inner and outer membranes of the cell. The three components of these tripartite systems are an inner-membrane, substrate-binding transporter (or pump); a periplasmic membrane fusion protein (or adaptor); and an outer-membrane-anchored channel. These three efflux proteins interact in the periplasmic space to form the three-part complexes. We previously presented the crystal structures of both the inner-membrane transporter CusA and membrane fusion protein CusB of the CusCBA tripartite efflux system from Escherichia coli. We also described the co-crystal structure of the CusBA adaptor-transporter, revealing that the trimeric CusA efflux pump assembles with six CusB protein molecules to form the complex CusB(6)-CusA(3). We here report three different conformers of the crystal structures of CusBA-Cu(I), suggesting a mechanism on how Cu(I) binding initiates a sequence of conformational transitions in the transport cycle. Genetic analysis and transport assays indicate that charged residues, in addition to the methionine pairs and clusters, are essential for extruding metal ions out of the cell.
PDB ID: 3T51Download
MMDB ID: 100652
PDB Deposition Date: 2011/7/26
Updated in MMDB: 2012/09
Experimental Method:
x-ray diffraction
Resolution: 3.9  Å
Source Organism:
Similar Structures:
Biological Unit for 3T51: trimeric; determined by author and by software (PISA)
Molecular Components in 3T51
Label Count Molecule
Proteins (3 molecules)
Cation Efflux System Protein Cusb(Gene symbol: cusB)
Molecule annotation
Cation Efflux System Protein Cusa(Gene symbol: cusA)
Molecule annotation
Chemicals (2 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB