4LCU

Structure of KcsA with E118A mutation

Summary for 4LCU

• Entry DOI: 10.2210/pdb4lcu/pdb
• Related: 4LBE
• Descriptor: Fab light chain, Fab heavy chain, pH-gated potassium channel KcsA, ... (6 entities in total)
• Functional Keywords: voltage gated potassium channel, potassium channel, transport protein, membrane protein, ph-gated potassium channel
• Biological source: Mus musculus (mouse); More
• Cellular location: Cell membrane; Multi-pass membrane protein: P0A334
• Total number of polymer chains: 3
• Total formula weight: 61812.14

Authors

Nimigean, C.M.,Posson, D.J.,McCoy, J.M. (deposition date: 2013-06-23, release date: 2013-10-30, Last modification date: 2017-11-15)

Primary citation

Posson, D.J.,Thompson, A.N.,McCoy, J.G.,Nimigean, C.M.
Molecular interactions involved in proton-dependent gating in KcsA potassium channels.
J.Gen.Physiol., 142:613-624, 2013

PubMed Abstract: The bacterial potassium channel KcsA is gated open by the binding of protons to amino acids on the intracellular side of the channel. We have identified, via channel mutagenesis and x-ray crystallography, two pH-sensing amino acids and a set of nearby residues involved in molecular interactions that influence gating. We found that the minimal mutation of one histidine (H25) and one glutamate (E118) near the cytoplasmic gate completely abolished pH-dependent gating. Mutation of nearby residues either alone or in pairs altered the channel's response to pH. In addition, mutations of certain pairs of residues dramatically increased the energy barriers between the closed and open states. We proposed a Monod-Wyman-Changeux model for proton binding and pH-dependent gating in KcsA, where H25 is a "strong" sensor displaying a large shift in pKa between closed and open states, and E118 is a "weak" pH sensor. Modifying model parameters that are involved in either the intrinsic gating equilibrium or the pKa values of the pH-sensing residues was sufficient to capture the effects of all mutations.

PubMed: 24218397
DOI: 10.1085/jgp.201311057

Experimental method

X-RAY DIFFRACTION (2.752 Å)