Crystal structures of the response regulator DosR from Mycobacterium tuberculosis suggest a helix rearrangement mechanism for phosphorylation activation.
The response regulator DosR is essential for promoting long-term survival of Mycobacterium tuberculosis under low oxygen conditions in a dormant state and may be responsible for latent tuberculosis in one-third of the world's population. Here, we report crystal structures of full-length unphosphorylated DosR at 2.2 A resolution and its C-terminal DNA-binding domain at 1.7 A resolution. The full-length DosR structure reveals several features never seen before in other response regulators. The N-terminal domain of the full-length DosR structure has an unexpected (beta alpha)(4) topology instead of the canonical (beta alpha)(5) fold observed in other response regulators. The linker region adopts a unique conformation that contains two helices forming a four-helix bundle with two helices from another subunit, resulting in dimer formation. The C-terminal domain in the full-length DosR structure displays a novel location of helix alpha 10, which allows Gln199 to interact with the catalytic Asp54 residue of the N-terminal domain. In contrast, the structure of the DosR C-terminal domain alone displays a remarkable unstructured conformation for helix alpha 10 residues, different from the well-defined helical conformations in all other known structures, indicating considerable flexibility within the C-terminal domain. Our structures suggest a mode of DosR activation by phosphorylation via a helix rearrangement mechanism.
Wisedchaisri
Goragot
G
Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA.
Wu
Meiting
M
Sherman
David R
DR
Hol
Wim G J
WG
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D019281:Dimerization; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; C516838:Dev R protein, Mycobacterium tuberculosis