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2bs3

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2bs3, resolution 2.19Å ()
Sites: , , , , , , , , , , , , , , , , and
Ligands: , , , , , , ,
Activity: Succinate dehydrogenase, with EC number 1.3.99.1
Related: 1e7p, 1qla, 1qlb, 2bs2, 2bs4
Resources: FirstGlance, OCA, PDBsum, RCSB
Coordinates: save as pdb, mmCIF, xml



GLU C180 -> GLN VARIANT QUINOL:FUMARATE REDUCTASE FROM WOLINELLA SUCCINOGENES

Publication Abstract from PubMed

Reconciliation of apparently contradictory experimental results obtained on the quinol:fumarate reductase, a diheme-containing respiratory membrane protein complex from Wolinella succinogenes, was previously obtained by the proposal of the so-called "E pathway hypothesis." According to this hypothesis, transmembrane electron transfer via the heme groups is strictly coupled to cotransfer of protons via a transiently established pathway thought to contain the side chain of residue Glu-C180 as the most prominent component. Here we demonstrate that, after replacement of Glu-C180 with Gln or Ile by site-directed mutagenesis, the resulting mutants are unable to grow on fumarate, and the membrane-bound variant enzymes lack quinol oxidation activity. Upon solubilization, however, the purified enzymes display approximately 1/10 of the specific quinol oxidation activity of the wild-type enzyme and unchanged quinol Michaelis constants, K(m). The refined x-ray crystal structures at 2.19 A and 2.76 A resolution, respectively, rule out major structural changes to account for these experimental observations. Changes in the oxidation-reduction heme midpoint potential allow the conclusion that deprotonation of Glu-C180 in the wild-type enzyme facilitates the reoxidation of the reduced high-potential heme. Comparison of solvent isotope effects indicates that a rate-limiting proton transfer step in the wild-type enzyme is lost in the Glu-C180 --> Gln variant. The results provide experimental evidence for the validity of the E pathway hypothesis and for a crucial functional role of Glu-C180.

Experimental support for the "E pathway hypothesis" of coupled transmembrane e- and H+ transfer in dihemic quinol:fumarate reductase., Lancaster CR, Sauer US, Gross R, Haas AH, Graf J, Schwalbe H, Mantele W, Simon J, Madej MG, Proc Natl Acad Sci U S A. 2005 Dec 27;102(52):18860-5. PMID:16380425

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

About this Structure

2bs3 is a 6 chain structure with sequence from Wolinella succinogenes. Full crystallographic information is available from OCA.

Reference

  • Lancaster CR, Sauer US, Gross R, Haas AH, Graf J, Schwalbe H, Mantele W, Simon J, Madej MG. Experimental support for the "E pathway hypothesis" of coupled transmembrane e- and H+ transfer in dihemic quinol:fumarate reductase. Proc Natl Acad Sci U S A. 2005 Dec 27;102(52):18860-5. PMID:16380425 doi:10.1073/pnas.0509711102
  • Lancaster CR. Wolinella succinogenes quinol:fumarate reductase and its comparison to E. coli succinate:quinone reductase. FEBS Lett. 2003 Nov 27;555(1):21-8. PMID:14630313
  • Lancaster CR. Wolinella succinogenes quinol:fumarate reductase-2.2-A resolution crystal structure and the E-pathway hypothesis of coupled transmembrane proton and electron transfer. Biochim Biophys Acta. 2002 Oct 11;1565(2):215-31. PMID:12409197
  • Lancaster CR, Gross R, Simon J. A third crystal form of Wolinella succinogenes quinol:fumarate reductase reveals domain closure at the site of fumarate reduction. Eur J Biochem. 2001 Mar;268(6):1820-7. PMID:11248702
  • Lancaster CR, Gorss R, Haas A, Ritter M, Mantele W, Simon J, Kroger A. Essential role of Glu-C66 for menaquinol oxidation indicates transmembrane electrochemical potential generation by Wolinella succinogenes fumarate reductase. Proc Natl Acad Sci U S A. 2000 Nov 21;97(24):13051-6. PMID:11186225
  • Lancaster CR, Kroger A, Auer M, Michel H. Structure of fumarate reductase from Wolinella succinogenes at 2.2 A resolution. Nature. 1999 Nov 25;402(6760):377-85. PMID:10586875 doi:10.1038/46483

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