1nm5
From Proteopedia
(New page: 200px<br /><applet load="1nm5" size="450" color="white" frame="true" align="right" spinBox="true" caption="1nm5, resolution 2.40Å" /> '''R. rubrum transhydro...) |
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| - | [[Image:1nm5.jpg|left|200px]]<br /><applet load="1nm5" size=" | + | [[Image:1nm5.jpg|left|200px]]<br /><applet load="1nm5" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1nm5, resolution 2.40Å" /> | caption="1nm5, resolution 2.40Å" /> | ||
'''R. rubrum transhydrogenase (dI.Q132N)2(dIII)1 asymmetric complex'''<br /> | '''R. rubrum transhydrogenase (dI.Q132N)2(dIII)1 asymmetric complex'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Transhydrogenase, found in bacterial membranes and inner mitochondrial | + | Transhydrogenase, found in bacterial membranes and inner mitochondrial membranes of animal cells, couples the redox reaction between NAD(H) and NADP(H) to proton translocation. In this work, the invariant Gln132 in the NAD(H)-binding component (dI) of the Rhodospirillum rubrum transhydrogenase was substituted with Asn (to give dI.Q132N). Mixtures of the mutant protein and the NADP(H)-binding component (dIII) of the enzyme readily produced an asymmetric complex, (dI.Q132N)(2)dIII(1). The X-ray structure of the complex revealed specific changes in the interaction between bound nicotinamide nucleotides and the protein at the hydride transfer site. The first-order rate constant of the redox reaction between nucleotides bound to (dI.Q132N)(2)dIII(1) was <1% of that for the wild-type complex, and the deuterium isotope effect was significantly decreased. The nucleotide binding properties of the dI component in the complex were asymmetrically affected by the Gln-to-Asn mutation. In intact, membrane-bound transhydrogenase, the substitution completely abolished all catalytic activity. The results suggest that Gln132 in the wild-type enzyme behaves as a "tether" or a "tie" in the mutual positioning of the (dihydro)nicotinamide rings of NAD(H) and NADP(H) for hydride transfer during the conformational changes that are coupled to the translocation of protons across the membrane. This ensures that hydride transfer is properly gated and does not take place in the absence of proton translocation. |
==About this Structure== | ==About this Structure== | ||
| - | 1NM5 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodospirillum_rubrum Rhodospirillum rubrum] with NAD, NAP and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/NAD(P)(+)_transhydrogenase_(AB-specific) NAD(P)(+) transhydrogenase (AB-specific)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.6.1.2 1.6.1.2] Full crystallographic information is available from [http:// | + | 1NM5 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodospirillum_rubrum Rhodospirillum rubrum] with <scene name='pdbligand=NAD:'>NAD</scene>, <scene name='pdbligand=NAP:'>NAP</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/NAD(P)(+)_transhydrogenase_(AB-specific) NAD(P)(+) transhydrogenase (AB-specific)], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.6.1.2 1.6.1.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NM5 OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Rhodospirillum rubrum]] | [[Category: Rhodospirillum rubrum]] | ||
| - | [[Category: Boxel, G | + | [[Category: Boxel, G I.Van.]] |
| - | [[Category: Cotton, N | + | [[Category: Cotton, N P.]] |
| - | [[Category: Jackson, J | + | [[Category: Jackson, J B.]] |
| - | [[Category: Quirk, P | + | [[Category: Quirk, P G.]] |
| - | [[Category: White, S | + | [[Category: White, S A.]] |
[[Category: GOL]] | [[Category: GOL]] | ||
[[Category: NAD]] | [[Category: NAD]] | ||
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[[Category: rossman domain]] | [[Category: rossman domain]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:07:39 2008'' |
Revision as of 12:07, 21 February 2008
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R. rubrum transhydrogenase (dI.Q132N)2(dIII)1 asymmetric complex
Overview
Transhydrogenase, found in bacterial membranes and inner mitochondrial membranes of animal cells, couples the redox reaction between NAD(H) and NADP(H) to proton translocation. In this work, the invariant Gln132 in the NAD(H)-binding component (dI) of the Rhodospirillum rubrum transhydrogenase was substituted with Asn (to give dI.Q132N). Mixtures of the mutant protein and the NADP(H)-binding component (dIII) of the enzyme readily produced an asymmetric complex, (dI.Q132N)(2)dIII(1). The X-ray structure of the complex revealed specific changes in the interaction between bound nicotinamide nucleotides and the protein at the hydride transfer site. The first-order rate constant of the redox reaction between nucleotides bound to (dI.Q132N)(2)dIII(1) was <1% of that for the wild-type complex, and the deuterium isotope effect was significantly decreased. The nucleotide binding properties of the dI component in the complex were asymmetrically affected by the Gln-to-Asn mutation. In intact, membrane-bound transhydrogenase, the substitution completely abolished all catalytic activity. The results suggest that Gln132 in the wild-type enzyme behaves as a "tether" or a "tie" in the mutual positioning of the (dihydro)nicotinamide rings of NAD(H) and NADP(H) for hydride transfer during the conformational changes that are coupled to the translocation of protons across the membrane. This ensures that hydride transfer is properly gated and does not take place in the absence of proton translocation.
About this Structure
1NM5 is a Protein complex structure of sequences from Rhodospirillum rubrum with , and as ligands. Active as NAD(P)(+) transhydrogenase (AB-specific), with EC number 1.6.1.2 Full crystallographic information is available from OCA.
Reference
Glutamine 132 in the NAD(H)-binding component of proton-translocating transhydrogenase tethers the nucleotides before hydride transfer., van Boxel GI, Quirk PG, Cotton NP, White SA, Jackson JB, Biochemistry. 2003 Feb 11;42(5):1217-26. PMID:12564924
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