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Small-angle X-ray Scattering Study of a Rex Family Repressor: Conformational Response to NADH and NAD(+) Binding in Solution.

Wang, Ellen LU ; Ikonen, Teemu P; Knaapila, Matti LU ; Svergun, Dmitri; Logan, Derek LU and von Wachenfeldt, Claes LU (2011) In Journal of Molecular Biology 408. p.670-683
Abstract
The transcriptional repressor Rex is a sensor of the intracellular NADH/NAD(+) redox state through direct binding of NADH or NAD(+). Homodimeric Rex protein from Thermus aquaticus (T-Rex) and Bacillus subtilis (B-Rex) exists in several different conformations. In both organisms, Rex in complex with NADH has the DNA binding domains packed together at the dimer interface, whereas in the apo form of B-Rex the linkers connecting these domains to the core are flexible. The crystal structures of the apo forms of B-Rex and a mutated variant of T-Rex are radically different. We describe the solution structures of B-Rex in complex with NAD(+) or NADH and in its apo form, on the basis of small-angle X-ray scattering (SAXS) measurements. This study... (More)
The transcriptional repressor Rex is a sensor of the intracellular NADH/NAD(+) redox state through direct binding of NADH or NAD(+). Homodimeric Rex protein from Thermus aquaticus (T-Rex) and Bacillus subtilis (B-Rex) exists in several different conformations. In both organisms, Rex in complex with NADH has the DNA binding domains packed together at the dimer interface, whereas in the apo form of B-Rex the linkers connecting these domains to the core are flexible. The crystal structures of the apo forms of B-Rex and a mutated variant of T-Rex are radically different. We describe the solution structures of B-Rex in complex with NAD(+) or NADH and in its apo form, on the basis of small-angle X-ray scattering (SAXS) measurements. This study addresses to what extent the unusual orientation of the DNA recognition domains of the crystal structure of apo B-Rex is owing to stabilization by crystal packing. Low-resolution ab initio solution structures were obtained for apo B-Rex, B-Rex:NADH and B-Rex:NAD(+). Models giving a more detailed picture of these three solution structures were obtained also by rigid body fitting of the crystallographic domains. The SAXS data confirm the elongated and flexible nature of apo-B-Rex and the existence of two distinct and more rigid conformations for the complexes with NADH and NAD(+). The models emerging from this study indicate a reaction mechanism for B-Rex in which the recognition domains are rotated upon binding to NADH. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Molecular Biology
volume
408
pages
670 - 683
publisher
Elsevier
external identifiers
  • wos:000290501200007
  • scopus:79955031175
ISSN
1089-8638
DOI
10.1016/j.jmb.2011.02.050
language
English
LU publication?
yes
id
81ce36b0-1f90-4b97-8326-3dfcd64090b8 (old id 1883972)
date added to LUP
2011-04-11 13:26:37
date last changed
2017-01-01 03:23:49
@article{81ce36b0-1f90-4b97-8326-3dfcd64090b8,
  abstract     = {The transcriptional repressor Rex is a sensor of the intracellular NADH/NAD(+) redox state through direct binding of NADH or NAD(+). Homodimeric Rex protein from Thermus aquaticus (T-Rex) and Bacillus subtilis (B-Rex) exists in several different conformations. In both organisms, Rex in complex with NADH has the DNA binding domains packed together at the dimer interface, whereas in the apo form of B-Rex the linkers connecting these domains to the core are flexible. The crystal structures of the apo forms of B-Rex and a mutated variant of T-Rex are radically different. We describe the solution structures of B-Rex in complex with NAD(+) or NADH and in its apo form, on the basis of small-angle X-ray scattering (SAXS) measurements. This study addresses to what extent the unusual orientation of the DNA recognition domains of the crystal structure of apo B-Rex is owing to stabilization by crystal packing. Low-resolution ab initio solution structures were obtained for apo B-Rex, B-Rex:NADH and B-Rex:NAD(+). Models giving a more detailed picture of these three solution structures were obtained also by rigid body fitting of the crystallographic domains. The SAXS data confirm the elongated and flexible nature of apo-B-Rex and the existence of two distinct and more rigid conformations for the complexes with NADH and NAD(+). The models emerging from this study indicate a reaction mechanism for B-Rex in which the recognition domains are rotated upon binding to NADH.},
  author       = {Wang, Ellen and Ikonen, Teemu P and Knaapila, Matti and Svergun, Dmitri and Logan, Derek and von Wachenfeldt, Claes},
  issn         = {1089-8638},
  language     = {eng},
  pages        = {670--683},
  publisher    = {Elsevier},
  series       = {Journal of Molecular Biology},
  title        = {Small-angle X-ray Scattering Study of a Rex Family Repressor: Conformational Response to NADH and NAD(+) Binding in Solution.},
  url          = {http://dx.doi.org/10.1016/j.jmb.2011.02.050},
  volume       = {408},
  year         = {2011},
}