@article{5ca5021c35ff4e64926cf92545ba8fcf,
title = "X-ray structure of a Rex-family repressor/NADH complex insights into the mechanism of redox sensing",
abstract = "The redox-sensing repressor Rex regulates transcription of respiratory genes in response to the intra cellular NADH/NAD + redox poise. As a step toward elucidating the molecular mechanism of NADH/NAD + sensing, the X-ray structure of Thermus aquaticus Rex (T-Rex) bound to effector NADH has been determined at 2.9 {\AA} resolution. The fold of the C-terminal domain of T-Rex is characteristic of NAD(H)-dependent enzymes, whereas the N-terminal domain is similar to a winged helix DNA binding motif. T-Rex dimerization is primarily mediated by {"}domain-swapped{"} α helices. Each NADH molecule binds to the C-terminal domain near the dimer interface. In contrast to NAD(H)-dependent enzymes, the nicotinamide is deeply buried within a hydrophobic pocket that appears to preclude substrate entry. We show that T-Rex binds to the Rex operator, and NADH but not NAD + inhibits T-Rex/DNA binding activity. A mechanism for redox sensing by Rex family members is proposed by analogy with domain closure of NAD(H)-dependent enzymes.",
author = "Sickmier, {E. Allen} and Dimitris Brekasis and Shanthi Paranawithana and Bonanno, {Jeffrey B.} and Paget, {Mark S.B.} and Burley, {Stephen K.} and Kielkopf, {Clara L.}",
note = "Funding Information: At the NSLS, we thank Dr. K.R. Rajashankar for assistance using Beamline X9A. We are grateful to Dr. X. Du for providing the pTP253 expression plasmid. We thank Dr. R.L. McMacken, L. Mull, and Dr. J.E. Wedekind for insightful discussions. This structure was determined and initially refined as target T744 in the Burley Laboratory at The Rockefeller University under the auspices of the NIGMS funded Protein Structure Initiative by the New York Structural Genomics Research Consortium supported by an NIH Center Grant P50 GM-62529 (S.K.B.). Details of the refinement and subsequent functional analysis were completed collaboratively between the Kielkopf Laboratory at Johns Hopkins University and the Paget Laboratory at University of Sussex. E.A.S. is a Calvin A. Lang Fellow. S.K.B. was also a member of the Howard Hughes Medical Institute. Work in the Paget Laboratory was supported by BBSRC grant P19928. ",
year = "2005",
month = jan,
doi = "10.1016/j.str.2004.10.012",
language = "English (US)",
volume = "13",
pages = "43--54",
journal = "Structure with Folding & design",
issn = "0969-2126",
publisher = "Cell Press",
number = "1",
}