5DDG: The Structure Of Transcriptional Factor Arar From Bacteroides Thetaiotaomicron Vpi In Complex With Target Double Strand Dna

Citation:
Abstract
Carbohydrate metabolism plays a crucial role in the ecophysiology of human gut microbiota. Mechanisms of transcriptional regulation of sugar catabolism in commensal and prevalent human gut bacteria such as Bacteroides thetaiotaomicron remain mostly unknown. By a combination of bioinformatics and experimental approaches, we have identified an NrtR family transcription factor (BT0354 in B. thetaiotaomicron, BtAraR) as a novel regulator controlling the arabinose utilization genes. L-arabinose was confirmed to be a negative effector of BtAraR. We have solved the crystal structures of the apo and L-arabinose-bound BtAraR proteins, as well as the complex of apo-protein with a specific DNA operator. BtAraR forms a homodimer with each subunit comprised of the ligand-binding Nudix hydrolase-like domain and the DNA-binding winged-helix-turn-helix (wHTH) domain. We have identified the residues involved in binding of L-arabinose and recognition of DNA. The majority of these residues are well conserved in the AraR orthologs in Bacteroidetes. In the structure of the BtAraR-DNA complex, we found the unique interaction of arginine intercalating its guanidinum moiety into the base pair stacking of B-DNA. L-arabinose binding induces movement of wHTH domains, resulting in a conformation unsuitable for DNA binding. Our analysis facilitates reconstruction of the metabolic and regulatory networks involved in carbohydrate utilization in human gut Bacteroides.
PDB ID: 5DDGDownload
MMDB ID: 132557
PDB Deposition Date: 2015/8/24
Updated in MMDB: 2015/12
Experimental Method:
x-ray diffraction
Resolution: 3.06  Å
Source Organism:
Similar Structures:
Biological Unit for 5DDG: tetrameric; determined by author
Molecular Components in 5DDG
Label Count Molecule
Proteins (2 molecules)
2
Transcriptional Factor Arar
Molecule annotation
Nucleotides(2 molecules)
1
DNA (27-mer)
Molecule annotation
1
DNA (27-mer)
Molecule annotation
Chemicals (4 molecules)
1
2
2
2
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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