3T51

Crystal structures of the pre-extrusion and extrusion states of the CusBA adaptor-transporter complex

Summary for 3T51

• Entry DOI: 10.2210/pdb3t51/pdb
• Related: 3T53 3T56
• Descriptor: Cation efflux system protein CusB, Cation efflux system protein CusA, COPPER (II) ION (3 entities in total)
• Functional Keywords: transmembrane helix, heavy metal efflux, transport protein
• Biological source: Escherichia coli; More
• Cellular location: Cell inner membrane; Multi-pass membrane protein (Potential): P38054
• Total number of polymer chains: 3
• Total formula weight: 189061.17

Authors

Su, C.-C.,Long, F.,Yu, E.W. (deposition date: 2011-07-26, release date: 2012-06-20, Last modification date: 2024-02-28)

Primary citation

Su, C.C.,Long, F.,Lei, H.T.,Bolla, J.R.,Do, S.V.,Rajashankar, K.R.,Yu, E.W.
Charged Amino Acids (R83, E567, D617, E625, R669, and K678) of CusA Are Required for Metal Ion Transport in the Cus Efflux System.
J.Mol.Biol., 422:429-441, 2012

PubMed Abstract: 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.

PubMed: 22683351
DOI: 10.1016/j.jmb.2012.05.038

Experimental method

X-RAY DIFFRACTION (3.9 Å)