4lml

From Proteopedia

Jump to: navigation, search

GLIC double mutant I9'A T25'A

Structural highlights

4lml is a 5 chain structure with sequence from Gloeobacter violaceus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 3.8Å
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

GLIC_GLOVI Cationic channel with similar permeabilities for Na(+) and K(+), that is activated by an increase of the proton concentration on the extracellular side. Displays no permeability for chloride ions. Shows slow kinetics of activation, no desensitization and a single channel conductance of 8 pS. Might contribute to adaptation to external pH change.[1]

Publication Abstract from PubMed

Cryoelectron microscopy and X-ray crystallography have recently been used to generate structural models that likely represent the unliganded closed-channel conformation and the fully liganded open-channel conformation of different members of the nicotinic-receptor superfamily. To characterize the structure of the closed-channel conformation in its liganded state, we identified a number of positions in the loop between transmembrane segments 2 (M2) and 3 (M3) of a proton-gated ortholog from the bacterium Gloeobacter violaceus (GLIC) where mutations to alanine reduce the liganded-gating equilibrium constant, and solved the crystal structures of two such mutants (T25'A and Y27'A) at pH approximately 4.0. At the level of backbone atoms, the liganded closed-channel model presented here differs from the liganded open-channel structure of GLIC in the pre-M1 linker, the M3-M4 loop, and much more prominently, in the extracellular half of the pore lining, where the more pronounced tilt of the closed-channel M2 alpha-helices toward the pore's long axis narrows the permeation pathway. On the other hand, no differences between the liganded closed-channel and open-channel models could be detected at the level of the extracellular domain, where conformational changes are expected to underlie the low-to-high proton-affinity switch that drives gating of proton-bound channels. Thus, the liganded closed-channel model is nearly indistinguishable from the recently described "locally closed" structure. However, because cross-linking strategies (which could have stabilized unstable conformations) and mutations involving ionizable side chains (which could have affected proton-gated channel activation) were purposely avoided, we favor the notion that this structure represents one of the end states of liganded gating rather than an unstable intermediate.

Gating of the proton-gated ion channel from Gloeobacter violaceus at pH 4 as revealed by X-ray crystallography.,Gonzalez-Gutierrez G, Cuello LG, Nair SK, Grosman C Proc Natl Acad Sci U S A. 2013 Oct 28. PMID:24167270[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

Loading citation details..
No citations found

See Also

References

  1. Bocquet N, Prado de Carvalho L, Cartaud J, Neyton J, Le Poupon C, Taly A, Grutter T, Changeux JP, Corringer PJ. A prokaryotic proton-gated ion channel from the nicotinic acetylcholine receptor family. Nature. 2007 Jan 4;445(7123):116-9. Epub 2006 Dec 10. PMID:17167423 doi:10.1038/nature05371
  2. Gonzalez-Gutierrez G, Cuello LG, Nair SK, Grosman C. Gating of the proton-gated ion channel from Gloeobacter violaceus at pH 4 as revealed by X-ray crystallography. Proc Natl Acad Sci U S A. 2013 Oct 28. PMID:24167270 doi:http://dx.doi.org/10.1073/pnas.1313156110

Contents


PDB ID 4lml

Drag the structure with the mouse to rotate

Proteopedia Page Contributors and Editors (what is this?)

OCA

Personal tools