Conformational changes of ribose-binding protein and two related repressors are tailored to fit the functional need.
The structures and conformational changes of the periplasmic ribose-binding protein and two repressors, PurR and LacI, were compared. Although the closed, ligand-bound structures of the three proteins are very similar, they differ greatly in the degree and direction in which they open, as well as in the amount of internal rearrangement within the domains during that process. Water molecules and a relatively symmetrical inter-domain connection region assist in the large opening observed for the binding protein, while the design of the repressors appears to preclude such dramatic movements. The dimeric nature of the latter proteins, an important aspect in their binding of pseudo-symmetrical DNA sequences, also appears to be a determinant in the allowed motion. Slight differences in the structure of PurR and LacI explain how they can converge to a similar DNA-binding state in response to different binding states of their small molecule effector.
Mowbray
S L
SL
Department of Molecular Biology, Swedish Agricultural University, Uppsala, S-75124, Sweden. mowbray@xray.bmc.uu.se
Björkman
A J
AJ
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D029968:Escherichia coli Proteins; D056968:Lac Repressors; D008969:Molecular Sequence Data; D033902:Periplasmic Binding Proteins; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D056968:Lac Repressors; D033902:Periplasmic Binding Proteins; C065825:PurR protein, Bacteria; C489317:PurR protein, E coli; C028003:RbsB protein, E coli; D012097:Repressor Proteins