1k6n: Difference between revisions

Revision as of 14:30, 21 February 2008

E(L212)A,D(L213)A Double Mutant Structure of Photosynthetic Reaction Center from Rhodobacter Sphaeroides

OverviewOverview

We report on the unexpected structural changes caused by substitution of acidic amino acids in the Q(B) binding pocket of the bacterial photosynthetic reaction center by alanines. The mutations targeted key residues L212Glu and L213Asp of this transmembrane protein-cofactor complex. The amino acid substitutions in the L212Ala-L213Ala mutant reaction center ("AA") were known to affect the delivery of protons after the light-induced generation of Q(B)(-), which renders the AA strain incapable of photosynthetic growth. The AA structure not only revealed side chain rearrangements but also showed movement of the main chain segments that are contiguous with the mutation sites. The alanine substitutions caused an expansion of the cavity rather than its collapse. In addition, Q(B) is found mainly in the binding site that is proximal to the iron-ligand complex (closest to Q(A)) as opposed to its distal binding site (furthest from Q(A)) in the structure of the wild-type reaction center. The observed rearrangements in the structure of the AA reaction center establish a new balance between charged residues of an interactive network near Q(B). This structurally and electrostatically altered complex forms the basis for future understanding of the structural basis for proton transfer in active reaction centers which retain the alanine substitutions but carry a distant compensatory mutation.

About this StructureAbout this Structure

1K6N is a Protein complex structure of sequences from Rhodobacter sphaeroides with , , , , , and as ligands. Full crystallographic information is available from OCA.

ReferenceReference

The structure of a mutant photosynthetic reaction center shows unexpected changes in main chain orientations and quinone position., Pokkuluri PR, Laible PD, Deng YL, Wong TN, Hanson DK, Schiffer M, Biochemistry. 2002 May 14;41(19):5998-6007. PMID:11993994

Page seeded by OCA on Thu Feb 21 13:30:45 2008

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

OCA

@@ Line 1: / Line 1: @@
-[[Image:1k6n.gif|left|200px]]<br /><applet load="1k6n" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1k6n.gif|left|200px]]<br /><applet load="1k6n" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1k6n, resolution 3.10&Aring;" />
 '''E(L212)A,D(L213)A Double Mutant Structure of Photosynthetic Reaction Center from Rhodobacter Sphaeroides'''<br />
 ==Overview==
-We report on the unexpected structural changes caused by substitution of, acidic amino acids in the Q(B) binding pocket of the bacterial, photosynthetic reaction center by alanines. The mutations targeted key, residues L212Glu and L213Asp of this transmembrane protein-cofactor, complex. The amino acid substitutions in the L212Ala-L213Ala mutant, reaction center ("AA") were known to affect the delivery of protons after, the light-induced generation of Q(B)(-), which renders the AA strain, incapable of photosynthetic growth. The AA structure not only revealed, side chain rearrangements but also showed movement of the main chain, segments that are contiguous with the mutation sites. The alanine, substitutions caused an expansion of the cavity rather than its collapse., In addition, Q(B) is found mainly in the binding site that is proximal to, the iron-ligand complex (closest to Q(A)) as opposed to its distal binding, site (furthest from Q(A)) in the structure of the wild-type reaction, center. The observed rearrangements in the structure of the AA reaction, center establish a new balance between charged residues of an interactive, network near Q(B). This structurally and electrostatically altered complex, forms the basis for future understanding of the structural basis for, proton transfer in active reaction centers which retain the alanine, substitutions but carry a distant compensatory mutation.
+We report on the unexpected structural changes caused by substitution of acidic amino acids in the Q(B) binding pocket of the bacterial photosynthetic reaction center by alanines. The mutations targeted key residues L212Glu and L213Asp of this transmembrane protein-cofactor complex. The amino acid substitutions in the L212Ala-L213Ala mutant reaction center ("AA") were known to affect the delivery of protons after the light-induced generation of Q(B)(-), which renders the AA strain incapable of photosynthetic growth. The AA structure not only revealed side chain rearrangements but also showed movement of the main chain segments that are contiguous with the mutation sites. The alanine substitutions caused an expansion of the cavity rather than its collapse. In addition, Q(B) is found mainly in the binding site that is proximal to the iron-ligand complex (closest to Q(A)) as opposed to its distal binding site (furthest from Q(A)) in the structure of the wild-type reaction center. The observed rearrangements in the structure of the AA reaction center establish a new balance between charged residues of an interactive network near Q(B). This structurally and electrostatically altered complex forms the basis for future understanding of the structural basis for proton transfer in active reaction centers which retain the alanine substitutions but carry a distant compensatory mutation.
 ==About this Structure==
-K6N is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodobacter_sphaeroides Rhodobacter sphaeroides] with FE, BCL, BPH, U10, SPN, CDL and LDA as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1K6N OCA].
+K6N is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodobacter_sphaeroides Rhodobacter sphaeroides] with <scene name='pdbligand=FE:'>FE</scene>, <scene name='pdbligand=BCL:'>BCL</scene>, <scene name='pdbligand=BPH:'>BPH</scene>, <scene name='pdbligand=U10:'>U10</scene>, <scene name='pdbligand=SPN:'>SPN</scene>, <scene name='pdbligand=CDL:'>CDL</scene> and <scene name='pdbligand=LDA:'>LDA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K6N OCA].
 ==Reference==
@@ Line 13: / Line 13: @@
 [[Category: Protein complex]]
 [[Category: Rhodobacter sphaeroides]]
-[[Category: Deng, Y.L.]]
+[[Category: Deng, Y L.]]
-[[Category: Hanson, D.K.]]
+[[Category: Hanson, D K.]]
-[[Category: Laible, P.D.]]
+[[Category: Laible, P D.]]
-[[Category: Pokkuluri, P.R.]]
+[[Category: Pokkuluri, P R.]]
 [[Category: Schiffer, M.]]
-[[Category: Wong, T.N.]]
+[[Category: Wong, T N.]]
 [[Category: BCL]]
 [[Category: BPH]]
@@ Line 30: / Line 30: @@
 [[Category: proton transfer]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 18:53:33 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:30:45 2008''