A conformational change in the isolated NADP(H)-binding component (dIII) of transhydrogenase induced by low pH: a reflection of events during proton translocation by the complete enzyme?

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@article{81a6144c1cb3475caf99dc0559b212ea,
title = "A conformational change in the isolated NADP(H)-binding component (dIII) of transhydrogenase induced by low pH: a reflection of events during proton translocation by the complete enzyme?",
abstract = "Transhydrogenase couples the reduction of NADP(+) by NADH to inward proton translocation across the bacterial (or mitochondrial) membrane. Conformational changes in the NADP(H)-binding component of the enzyme (dIII) are central to the coupling mechanism. In the {"}open{"} state, NADP(H) bound to dIII can readily exchange with nucleotides in the solvent but hydride transfer [to/from NAD(H) bound to dI] is prevented. In the {"}occluded{"} state, bound NADP(H) cannot exchange with solvent nucleotides but the hydride transfer reaction is permitted. It was previously found that the conformational state of isolated, recombinant dIII is pH dependent. At neutral pH, the protein adopts a conformation resembling the occluded state, and at low pH, it adopts a conformation resembling the open state. The crystal structure of dIII indicates that the loop E {"}lid{"} might be largely responsible for the very high affinity of the protein for NADP(H). In this paper we show, using fluorescence resonance energy transfer, that the distance between the apex of loop E of isolated dIII, and the core of the protein, increases when the solution pH is lowered. This is consistent with the view that the lid is retracted to permit NADPH release during turnover of the complete enzyme. (C) 2002 Elsevier Science B.V. All rights reserved.",
keywords = "redox protein, proton translocation, fluorescence resonance energy transfer, transhydrogenase",
author = "Daniel Rodrigues and John Jackson",
year = "2002",
month = sep
day = "10",
doi = "10.1016/S0005-2728(02)00247-5",
language = "English",
volume = "1555",
pages = "8--13",
journal = "Biochimica et Biophysica Acta",
issn = "1874-9399",
publisher = "Elsevier",
number = "1-3",

}

RIS

TY - JOUR

T1 - A conformational change in the isolated NADP(H)-binding component (dIII) of transhydrogenase induced by low pH: a reflection of events during proton translocation by the complete enzyme?

AU - Rodrigues, Daniel

AU - Jackson, John

PY - 2002/9/10

Y1 - 2002/9/10

N2 - Transhydrogenase couples the reduction of NADP(+) by NADH to inward proton translocation across the bacterial (or mitochondrial) membrane. Conformational changes in the NADP(H)-binding component of the enzyme (dIII) are central to the coupling mechanism. In the "open" state, NADP(H) bound to dIII can readily exchange with nucleotides in the solvent but hydride transfer [to/from NAD(H) bound to dI] is prevented. In the "occluded" state, bound NADP(H) cannot exchange with solvent nucleotides but the hydride transfer reaction is permitted. It was previously found that the conformational state of isolated, recombinant dIII is pH dependent. At neutral pH, the protein adopts a conformation resembling the occluded state, and at low pH, it adopts a conformation resembling the open state. The crystal structure of dIII indicates that the loop E "lid" might be largely responsible for the very high affinity of the protein for NADP(H). In this paper we show, using fluorescence resonance energy transfer, that the distance between the apex of loop E of isolated dIII, and the core of the protein, increases when the solution pH is lowered. This is consistent with the view that the lid is retracted to permit NADPH release during turnover of the complete enzyme. (C) 2002 Elsevier Science B.V. All rights reserved.

AB - Transhydrogenase couples the reduction of NADP(+) by NADH to inward proton translocation across the bacterial (or mitochondrial) membrane. Conformational changes in the NADP(H)-binding component of the enzyme (dIII) are central to the coupling mechanism. In the "open" state, NADP(H) bound to dIII can readily exchange with nucleotides in the solvent but hydride transfer [to/from NAD(H) bound to dI] is prevented. In the "occluded" state, bound NADP(H) cannot exchange with solvent nucleotides but the hydride transfer reaction is permitted. It was previously found that the conformational state of isolated, recombinant dIII is pH dependent. At neutral pH, the protein adopts a conformation resembling the occluded state, and at low pH, it adopts a conformation resembling the open state. The crystal structure of dIII indicates that the loop E "lid" might be largely responsible for the very high affinity of the protein for NADP(H). In this paper we show, using fluorescence resonance energy transfer, that the distance between the apex of loop E of isolated dIII, and the core of the protein, increases when the solution pH is lowered. This is consistent with the view that the lid is retracted to permit NADPH release during turnover of the complete enzyme. (C) 2002 Elsevier Science B.V. All rights reserved.

KW - redox protein

KW - proton translocation

KW - fluorescence resonance energy transfer

KW - transhydrogenase

UR - http://www.scopus.com/inward/record.url?scp=0037056031&partnerID=8YFLogxK

U2 - 10.1016/S0005-2728(02)00247-5

DO - 10.1016/S0005-2728(02)00247-5

M3 - Article

VL - 1555

SP - 8

EP - 13

JO - Biochimica et Biophysica Acta

JF - Biochimica et Biophysica Acta

SN - 1874-9399

IS - 1-3

ER -