1dv3: Difference between revisions

Revision as of 13:20, 21 February 2008

PHOTOSYNTHETIC REACTION CENTER FROM RHODOBACTER SPHAEROIDES IN THE CHARGE-SEPARATED D+QAQB-STATE WITH THE PROTON TRANSFER INHIBITOR CD2+

OverviewOverview

The reaction center (RC) from Rhodobacter sphaeroides couples light-driven electron transfer to protonation of a bound quinone acceptor molecule, Q(B), within the RC. The binding of Cd(2+) or Zn(2+) has been previously shown to inhibit the rate of reduction and protonation of Q(B). We report here on the metal binding site, determined by x-ray diffraction at 2.5-A resolution, obtained from RC crystals that were soaked in the presence of the metal. The structures were refined to R factors of 23% and 24% for the Cd(2+) and Zn(2+) complexes, respectively. Both metals bind to the same location, coordinating to Asp-H124, His-H126, and His-H128. The rate of electron transfer from Q(A)(-) to Q(B) was measured in the Cd(2+)-soaked crystal and found to be the same as in solution in the presence of Cd(2+). In addition to the changes in the kinetics, a structural effect of Cd(2+) on Glu-H173 was observed. This residue was well resolved in the x-ray structure-i.e., ordered-with Cd(2+) bound to the RC, in contrast to its disordered state in the absence of Cd(2+), which suggests that the mobility of Glu-H173 plays an important role in the rate of reduction of Q(B). The position of the Cd(2+) and Zn(2+) localizes the proton entry into the RC near Asp-H124, His-H126, and His-H128. Based on the location of the metal, likely pathways of proton transfer from the aqueous surface to Q(B) are proposed.

About this StructureAbout this Structure

1DV3 is a Protein complex structure of sequences from Rhodobacter sphaeroides with , , , , , and as ligands. Full crystallographic information is available from OCA.

ReferenceReference

Determination of the binding sites of the proton transfer inhibitors Cd2+ and Zn2+ in bacterial reaction centers., Axelrod HL, Abresch EC, Paddock ML, Okamura MY, Feher G, Proc Natl Acad Sci U S A. 2000 Feb 15;97(4):1542-7. PMID:10677497

Page seeded by OCA on Thu Feb 21 12:20:54 2008

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OCA

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-[[Image:1dv3.gif|left|200px]]<br /><applet load="1dv3" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1dv3.gif|left|200px]]<br /><applet load="1dv3" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1dv3, resolution 2.50&Aring;" />
 '''PHOTOSYNTHETIC REACTION CENTER FROM RHODOBACTER SPHAEROIDES IN THE CHARGE-SEPARATED D+QAQB-STATE WITH THE PROTON TRANSFER INHIBITOR CD2+'''<br />
 ==Overview==
-The reaction center (RC) from Rhodobacter sphaeroides couples light-driven, electron transfer to protonation of a bound quinone acceptor molecule, Q(B), within the RC. The binding of Cd(2+) or Zn(2+) has been previously, shown to inhibit the rate of reduction and protonation of Q(B). We report, here on the metal binding site, determined by x-ray diffraction at 2.5-A, resolution, obtained from RC crystals that were soaked in the presence of, the metal. The structures were refined to R factors of 23% and 24% for the, Cd(2+) and Zn(2+) complexes, respectively. Both metals bind to the same, location, coordinating to Asp-H124, His-H126, and His-H128. The rate of, electron transfer from Q(A)(-) to Q(B) was measured in the Cd(2+)-soaked, crystal and found to be the same as in solution in the presence of Cd(2+)., In addition to the changes in the kinetics, a structural effect of Cd(2+), on Glu-H173 was observed. This residue was well resolved in the x-ray, structure-i.e., ordered-with Cd(2+) bound to the RC, in contrast to its, disordered state in the absence of Cd(2+), which suggests that the, mobility of Glu-H173 plays an important role in the rate of reduction of, Q(B). The position of the Cd(2+) and Zn(2+) localizes the proton entry, into the RC near Asp-H124, His-H126, and His-H128. Based on the location, of the metal, likely pathways of proton transfer from the aqueous surface, to Q(B) are proposed.
+The reaction center (RC) from Rhodobacter sphaeroides couples light-driven electron transfer to protonation of a bound quinone acceptor molecule, Q(B), within the RC. The binding of Cd(2+) or Zn(2+) has been previously shown to inhibit the rate of reduction and protonation of Q(B). We report here on the metal binding site, determined by x-ray diffraction at 2.5-A resolution, obtained from RC crystals that were soaked in the presence of the metal. The structures were refined to R factors of 23% and 24% for the Cd(2+) and Zn(2+) complexes, respectively. Both metals bind to the same location, coordinating to Asp-H124, His-H126, and His-H128. The rate of electron transfer from Q(A)(-) to Q(B) was measured in the Cd(2+)-soaked crystal and found to be the same as in solution in the presence of Cd(2+). In addition to the changes in the kinetics, a structural effect of Cd(2+) on Glu-H173 was observed. This residue was well resolved in the x-ray structure-i.e., ordered-with Cd(2+) bound to the RC, in contrast to its disordered state in the absence of Cd(2+), which suggests that the mobility of Glu-H173 plays an important role in the rate of reduction of Q(B). The position of the Cd(2+) and Zn(2+) localizes the proton entry into the RC near Asp-H124, His-H126, and His-H128. Based on the location of the metal, likely pathways of proton transfer from the aqueous surface to Q(B) are proposed.
 ==About this Structure==
-DV3 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, CD, CL, BCL, BPH, U10 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=1DV3 OCA].
+DV3 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=CD:'>CD</scene>, <scene name='pdbligand=CL:'>CL</scene>, <scene name='pdbligand=BCL:'>BCL</scene>, <scene name='pdbligand=BPH:'>BPH</scene>, <scene name='pdbligand=U10:'>U10</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=1DV3 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: Feher, G.]]
-[[Category: Okamura, M.Y.]]
+[[Category: Okamura, M Y.]]
-[[Category: Paddock, M.L.]]
+[[Category: Paddock, M L.]]
 [[Category: BCL]]
 [[Category: BPH]]
@@ Line 33: / Line 33: @@
 [[Category: x-ray crystallography]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 13:36:32 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:20:54 2008''