3IKT

Crystal structure of a Rex-family repressor/DNA/NAD+ complex from Thermus aquaticus

Summary for 3IKT

• Entry DOI: 10.2210/pdb3ikt/pdb
• Related: 1XCB 3IKV 3IL2
• Descriptor: Redox-sensing transcriptional repressor rex, Rex operator DNA, NICOTINAMIDE-ADENINE-DINUCLEOTIDE, ... (4 entities in total)
• Functional Keywords: redox-sensing, winged helix, rossmann fold, nicotinamide adenine dinucleotide, nad, rex, thermus aquaticus, dna binding protein, cytoplasm, dna-binding, repressor, transcription, transcription regulation, dna binding protein-dna complex, dna binding protein/dna
• Biological source: Thermus thermophilus HB27; More
• Cellular location: Cytoplasm (Probable): Q72I39
• Total number of polymer chains: 4
• Total formula weight: 59631.01

Authors

McLaughlin, K.J.,Kielkopf, C.L. (deposition date: 2009-08-06, release date: 2010-06-09, Last modification date: 2023-09-06)

Primary citation

McLaughlin, K.J.,Strain-Damerell, C.M.,Xie, K.,Brekasis, D.,Soares, A.S.,Paget, M.S.,Kielkopf, C.L.
Structural basis for NADH/NAD+ redox sensing by a Rex family repressor.
Mol.Cell, 38:563-575, 2010

PubMed Abstract: Nicotinamide adenine dinucleotides have emerged as key signals of the cellular redox state. Yet the structural basis for allosteric gene regulation by the ratio of reduced NADH to oxidized NAD(+) is poorly understood. A key sensor among Gram-positive bacteria, Rex represses alternative respiratory gene expression until a limited oxygen supply elevates the intracellular NADH:NAD(+) ratio. Here we investigate the molecular mechanism for NADH/NAD(+) sensing among Rex family members by determining structures of Thermus aquaticus Rex bound to (1) NAD(+), (2) DNA operator, and (3) without ligand. Comparison with the Rex/NADH complex reveals that NADH releases Rex from the DNA site following a 40 degrees closure between the dimeric subunits. Complementary site-directed mutagenesis experiments implicate highly conserved residues in NAD-responsive DNA-binding activity. These rare views of a redox sensor in action establish a means for slight differences in the nicotinamide charge, pucker, and orientation to signal the redox state of the cell.

PubMed: 20513431
DOI: 10.1016/j.molcel.2010.05.006

Experimental method

X-RAY DIFFRACTION (2.26 Å)