Solution NMR structures reveal unique homodimer formation by a winged helix-turn-helix motif and provide first structures for protein domain family PF10771.
High-quality NMR structures of the homo-dimeric proteins Bvu3908 (69-residues in monomeric unit) from Bacteroides vulgatus and Bt2368 (74-residues) from Bacteroides thetaiotaomicron reveal the presence of winged helix-turn-helix (wHTH) motifs mediating tight complex formation. Such homo-dimer formation by winged HTH motifs is otherwise found only in two DNA-binding proteins with known structure: the C-terminal wHTH domain of transcriptional activator FadR from E. coli and protein TubR from B. thurigensis, which is involved in plasmid DNA segregation. However, the relative orientation of the wHTH motifs is different and residues involved in DNA-binding are not conserved in Bvu3908 and Bt2368. Hence, the proteins of the present study are not very likely to bind DNA, but are likely to exhibit a function that has thus far not been ascribed to homo-dimers formed by winged HTH motifs. The structures of Bvu3908 and Bt2368 are the first atomic resolution structures for PFAM family PF10771, a family of unknown function (DUF2582) currently containing 128 members.
Department of Chemistry, The State University of New York at Buffalo, and Northeast Structural Genomics Consortium, Buffalo, NY 14260, USA.
Alexander
A
Eletsky
Donald
D
Petrey
Qiangfeng Cliff
QC
Zhang
Hsiau-Wei
HW
Lee
Thomas B
TB
Acton
Rong
R
Xiao
John K
JK
Everett
James H
JH
Prestegard
Barry
B
Honig
Gaetano T
GT
Montelione
Thomas
T
Szyperski
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D001439:Bacteroides / Q000737:chemistry* / Q000235:genetics; D019077:Helix-Turn-Helix Motifs; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
D001426:Bacterial Proteins