The marked kinking of helix 4 decreases in the DNA-bound form. As compared with other TetR family members, AmtR has an extra C-terminal helix, a large extended external loop that resembles the flexible tranducer T-loop of GlnK in sequence, and a large open cavity towards the intersubunit region that changes shape upon DNA binding. AmtR has several unique structural features that appear to be invariant among AmtR proteins, which may be related to its regulation by the nitrogen-sensing trimeric protein GlnK rather than by small-molecule effectors.
These structures reveal an all-α homodimeric TetR family regulator composed of a helix–turn–helix-hosting N-terminal DNA-binding domain and a C-terminal dimerization domain. glutamicum, in apo (2.25-Å and 2.65-Å resolution) and DNA-bound (3-Å resolution) forms. Here, we report crystal structures of AmtR, the global nitrogen regulator of C.
Corynebacterium glutamicum is a bacterium used for industrial amino acid production, and understanding its metabolic pathway regulation is of high biotechnological interest.
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