4FG6

Structure of EcCLC E148A mutant in Glutamate

Summary for 4FG6

• Entry DOI: 10.2210/pdb4fg6/pdb
• Descriptor: H(+)/Cl(-) exchange transporter ClcA, Fab fragment (Heavy chain), Fab fragment (Light chain) (3 entities in total)
• Functional Keywords: transporter, membrane, transport protein
• Biological source: Escherichia coli K-12; More
• Cellular location: Cell inner membrane ; Multi- pass membrane protein : P37019
• Total number of polymer chains: 6
• Total formula weight: 193024.27

Authors

Feng, L.,MacKinnon, R. (deposition date: 2012-06-04, release date: 2012-07-04, Last modification date: 2023-09-13)

Primary citation

Feng, L.,Campbell, E.B.,MacKinnon, R.
Molecular mechanism of proton transport in CLC Cl-/H+ exchange transporters.
Proc.Natl.Acad.Sci.USA, 109:11699-11704, 2012

PubMed Abstract: CLC proteins underlie muscle, kidney, bone, and other organ system function by catalyzing the transport of Cl(-) ions across cell and organellar membranes. Some CLC proteins are ion channels while others are pumps that exchange Cl(-) for H(+). The pathway through which Cl(-) ions cross the membrane has been characterized, but the transport of H(+) and the principle by which their movement is coupled to Cl(-) movement is not well understood. Here we show that H(+) transport depends not only on the presence of a specific glutamate residue but also the presence of Cl(-) ions. H(+) transport, however, can be isolated and analyzed in the absence of Cl(-) by mutating the glutamate to alanine and adding carboxylate-containing molecules to solution, consistent with the notion that H(+) transfer is mediated through the entry of a carboxylate group into the anion pathway. Cl(-) ions and carboxylate interact with each other strongly. These data support a mechanism in which the glutamate carboxylate functions as a surrogate Cl(-) ion, but it can accept a H(+) and transfer it between the external solution and the central Cl(-) binding site, coupled to the movement of 2 Cl(-) ions.

PubMed: 22753511
DOI: 10.1073/pnas.1205764109

Experimental method

X-RAY DIFFRACTION (3.019 Å)