1nt5: Difference between revisions

Revision as of 02:56, 3 May 2008

F1-Gramicidin A in Sodium Dodecyl Sulfate Micelles (NMR)

OverviewOverview

To further investigate the effect of single amino acid substitution on the structure and function of the gramicidin channel, an analogue of gramicidin A (GA) has been synthesized in which Trp(15) is replaced by Gly in the critical aqueous interface and cation binding region. The structure of Gly(15)-GA incorporated into SDS micelles has been determined using a combination of 2D-NMR spectroscopy and molecular modeling. Like the parent GA, Gly(15)-GA forms a dimeric channel composed of two single-stranded, right-handed beta(6.3)-helices joined by hydrogen bonds between their N-termini. The replacement of Trp(15) by Gly does not have a significant effect on backbone structure or side chain conformations with the exception of Trp(11) in which the indole ring is rotated away from the channel axis. Measurement of the equilibrium binding constants and Delta G for the binding of monovalent cations to GA and Gly(15)-GA channels incorporated into PC vesicles using (205)Tl NMR spectroscopy shows that monovalent cations bind much more weakly to the Gly(15)-GA channel entrance than to GA channels. Utilizing the magnetization inversion transfer NMR technique, the transport of Na(+) ions through GA and Gly(15)-GA channels incorporated into PC/PG vesicles has been investigated. The Gly(15) substitution produces an increase in the activation enthalpy of transport and thus a significant decrease in the transport rate of the Na(+) ion is observed. The single-channel appearances show that the conducting channels have a single, well-defined structure. Consistent with the NMR results, the single-channel conductances are reduced by 30% and the lifetimes by 70%. It is concluded that the decrease in cation binding, transport, and conductance in Gly(15)-GA results from the removal of the Trp(15) dipole and, to a lesser extent, the change in orientation of Trp(11).

About this StructureAbout this Structure

Full crystallographic information is available from OCA.

ReferenceReference

The structure, cation binding, transport, and conductance of Gly15-gramicidin A incorporated into SDS micelles and PC/PG vesicles., Sham SS, Shobana S, Townsley LE, Jordan JB, Fernandez JQ, Andersen OS, Greathouse DV, Hinton JF, Biochemistry. 2003 Feb 18;42(6):1401-9. PMID:12578352 Page seeded by OCA on Sat May 3 02:56:57 2008

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA

@@ Line 1: / Line 1: @@
 [[Image:1nt5.jpg|left|200px]]
- {{Structure
+<!--
-|PDB= 1nt5 |SIZE=350|CAPTION= <scene name='initialview01'>1nt5</scene>
+The line below this paragraph, containing "STRUCTURE_1nt5", creates the "Structure Box" on the page.
-|SITE=
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND= <scene name='pdbligand=DLE:D-LEUCINE'>DLE</scene>, <scene name='pdbligand=DVA:D-VALINE'>DVA</scene>, <scene name='pdbligand=ETA:ETHANOLAMINE'>ETA</scene>, <scene name='pdbligand=FOR:FORMYL+GROUP'>FOR</scene>
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
-|ACTIVITY=
+or leave the SCENE parameter empty for the default display.
-|GENE=
+-->
-|DOMAIN=
+{{STRUCTURE_1nt5|  PDB=1nt5  |  SCENE=  }}
-|RELATEDENTRY=[[1jno|1JNO]], [[1jo3|1JO3]], [[1jo4|1JO4]], [[1ng8|1NG8]], [[1nt6|1NT6]]
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1nt5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1nt5 OCA], [http://www.ebi.ac.uk/pdbsum/1nt5 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1nt5 RCSB]</span>
-}}
 '''F1-Gramicidin A in Sodium Dodecyl Sulfate Micelles (NMR)'''
@@ Line 19: / Line 16: @@
 ==About this Structure==
-NT5 is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/ ]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NT5 OCA].
+Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NT5 OCA].
 ==Reference==
 The structure, cation binding, transport, and conductance of Gly15-gramicidin A incorporated into SDS micelles and PC/PG vesicles., Sham SS, Shobana S, Townsley LE, Jordan JB, Fernandez JQ, Andersen OS, Greathouse DV, Hinton JF, Biochemistry. 2003 Feb 18;42(6):1401-9. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12578352 12578352]
-[[Category: Protein complex]]
 [[Category: Fletcher, T G.]]
 [[Category: Hinton, J F.]]
 [[Category: Townsley, L E.]]
-[[Category: beta-6 3 helix]]
+[[Category: Beta-6 3 helix]]
-[[Category: linear gramicidin]]
+[[Category: Linear gramicidin]]
-[[Category: membrane ion channel]]
+[[Category: Membrane ion channel]]
-[[Category: peptide antibiotic]]
+[[Category: Peptide antibiotic]]
-[[Category: right-handed]]
+[[Category: Right-handed]]
-[[Category: sds micelle]]
+[[Category: Sds micelle]]
-[[Category: single-stranded helical dimer]]
+[[Category: Single-stranded helical dimer]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 02:56:57 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 22:35:12 2008''