1yf6: Difference between revisions

Revision as of 17:04, 21 February 2008

Structure of a quintuple mutant of photosynthetic reaction center from rhodobacter sphaeroides

OverviewOverview

The photosynthetic reaction center (RC) from purple bacteria converts light into chemical energy. Although the RC shows two nearly structurally symmetric branches, A and B, light-induced electron transfer in the native RC occurs almost exclusively along the A-branch to a primary quinone electron acceptor Q(A). Subsequent electron and proton transfer to a mobile quinone molecule Q(B) converts it to a quinol, Q(B)H(2). We report the construction and characterization of a series of mutants in Rhodobacter sphaeroides designed to reduce Q(B) via the B-branch. The quantum efficiency to Q(B) via the B-branch Phi(B) ranged from 0.4% in an RC containing the single mutation Ala-M260 --> Trp to 5% in a quintuple mutant which includes in addition three mutations to inhibit transfer along the A-branch (Gly-M203 --> Asp, Tyr-M210 --> Phe, Leu-M214 --> His) and one to promote transfer along the B-branch (Phe-L181 --> Tyr). Comparing the value of 0.4% for Phi(B) obtained in the AW(M260) mutant, which lacks Q(A), to the 100% quantum efficiency for Phi(A) along the A-branch in the native RC, we obtain a ratio for A-branch to B-branch electron transfer of 250:1. We determined the structure of the most effective (quintuple) mutant RC at 2.25 A (R-factor = 19.6%). The Q(A) site did not contain a quinone but was occupied by the side chain of Trp-M260 and a Cl(-). In this structure a nonfunctional quinone was found to occupy a new site near M258 and M268. The implications of this work to trap intermediate states are discussed.

About this StructureAbout this Structure

1YF6 is a Protein complex structure of sequences from Rhodobacter sphaeroides with , , , , , , , , , and as ligands. Full crystallographic information is available from OCA.

ReferenceReference

Quinone (QB) reduction by B-branch electron transfer in mutant bacterial reaction centers from Rhodobacter sphaeroides: quantum efficiency and X-ray structure., Paddock ML, Chang C, Xu Q, Abresch EC, Axelrod HL, Feher G, Okamura MY, Biochemistry. 2005 May 10;44(18):6920-8. PMID:15865437

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-[[Image:1yf6.gif|left|200px]]<br /><applet load="1yf6" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1yf6.gif|left|200px]]<br /><applet load="1yf6" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1yf6, resolution 2.25&Aring;" />
 '''Structure of a quintuple mutant of photosynthetic reaction center from rhodobacter sphaeroides'''<br />
 ==Overview==
-The photosynthetic reaction center (RC) from purple bacteria converts, light into chemical energy. Although the RC shows two nearly structurally, symmetric branches, A and B, light-induced electron transfer in the native, RC occurs almost exclusively along the A-branch to a primary quinone, electron acceptor Q(A). Subsequent electron and proton transfer to a, mobile quinone molecule Q(B) converts it to a quinol, Q(B)H(2). We report, the construction and characterization of a series of mutants in, Rhodobacter sphaeroides designed to reduce Q(B) via the B-branch. The, quantum efficiency to Q(B) via the B-branch Phi(B) ranged from 0.4% in an, RC containing the single mutation Ala-M260 --&gt; Trp to 5% in a quintuple, mutant which includes in addition three mutations to inhibit transfer, along the A-branch (Gly-M203 --&gt; Asp, Tyr-M210 --&gt; Phe, Leu-M214 --&gt; His), and one to promote transfer along the B-branch (Phe-L181 --&gt; Tyr)., Comparing the value of 0.4% for Phi(B) obtained in the AW(M260) mutant, which lacks Q(A), to the 100% quantum efficiency for Phi(A) along the, A-branch in the native RC, we obtain a ratio for A-branch to B-branch, electron transfer of 250:1. We determined the structure of the most, effective (quintuple) mutant RC at 2.25 A (R-factor = 19.6%). The Q(A), site did not contain a quinone but was occupied by the side chain of, Trp-M260 and a Cl(-). In this structure a nonfunctional quinone was found, to occupy a new site near M258 and M268. The implications of this work to, trap intermediate states are discussed.
+The photosynthetic reaction center (RC) from purple bacteria converts light into chemical energy. Although the RC shows two nearly structurally symmetric branches, A and B, light-induced electron transfer in the native RC occurs almost exclusively along the A-branch to a primary quinone electron acceptor Q(A). Subsequent electron and proton transfer to a mobile quinone molecule Q(B) converts it to a quinol, Q(B)H(2). We report the construction and characterization of a series of mutants in Rhodobacter sphaeroides designed to reduce Q(B) via the B-branch. The quantum efficiency to Q(B) via the B-branch Phi(B) ranged from 0.4% in an RC containing the single mutation Ala-M260 --&gt; Trp to 5% in a quintuple mutant which includes in addition three mutations to inhibit transfer along the A-branch (Gly-M203 --&gt; Asp, Tyr-M210 --&gt; Phe, Leu-M214 --&gt; His) and one to promote transfer along the B-branch (Phe-L181 --&gt; Tyr). Comparing the value of 0.4% for Phi(B) obtained in the AW(M260) mutant, which lacks Q(A), to the 100% quantum efficiency for Phi(A) along the A-branch in the native RC, we obtain a ratio for A-branch to B-branch electron transfer of 250:1. We determined the structure of the most effective (quintuple) mutant RC at 2.25 A (R-factor = 19.6%). The Q(A) site did not contain a quinone but was occupied by the side chain of Trp-M260 and a Cl(-). In this structure a nonfunctional quinone was found to occupy a new site near M258 and M268. The implications of this work to trap intermediate states are discussed.
 ==About this Structure==
-YF6 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 FE2, CL, PO4, BCL, BPH, U10, SPO, CDL, HTO, LDA and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1YF6 OCA].
+YF6 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=FE2:'>FE2</scene>, <scene name='pdbligand=CL:'>CL</scene>, <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=BCL:'>BCL</scene>, <scene name='pdbligand=BPH:'>BPH</scene>, <scene name='pdbligand=U10:'>U10</scene>, <scene name='pdbligand=SPO:'>SPO</scene>, <scene name='pdbligand=CDL:'>CDL</scene>, <scene name='pdbligand=HTO:'>HTO</scene>, <scene name='pdbligand=LDA:'>LDA</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1YF6 OCA].
 ==Reference==
@@ Line 13: / Line 13: @@
 [[Category: Protein complex]]
 [[Category: Rhodobacter sphaeroides]]
-[[Category: Abresch, E.C.]]
+[[Category: Abresch, E C.]]
-[[Category: Axelrod, H.L.]]
+[[Category: Axelrod, H L.]]
 [[Category: Chang, C.]]
-[[Category: Paddock, M.L.]]
+[[Category: Paddock, M L.]]
 [[Category: Xu, Q.]]
 [[Category: BCL]]
@@ Line 35: / Line 35: @@
 [[Category: rhodobacter sphaeroides]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 06:43:49 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:04:43 2008''