Crystal structures of RbsD leading to the identification of cytoplasmic sugar-binding proteins with a novel folding architecture.
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Kim MS, Shin J, Lee W, Lee HS, Oh BH
Crystal structures of RbsD leading to the identification of cytoplasmic sugar-binding proteins with a novel folding architecture.
J Biol Chem. 2003 Jul 25;278(30):28173-80. Epub 2003 May 8.
- PubMed ID
- 12738765 [ View in PubMed]
- Abstract
RbsD is the only protein whose biochemical function is unknown among the six gene products of the rbs operon involved in the active transport of ribose. FucU, a paralogue of RbsD conserved from bacteria to human, is also the only protein whose function is unknown among the seven gene products of the l-fucose regulon. Here we report the crystal structures of Bacillus subtilis RbsD, which reveals a novel decameric toroidal assembly of the protein. Nuclear magnetic resonance and other studies on RbsD reveal that the intersubunit cleft of the protein binds specific forms of d-ribose, but it does not have an enzyme activity toward the sugar. Likewise, FucU binds l-fucose but lacks an enzyme activity toward this sugar. We conclude that RbsD and FucU are cytoplasmic sugar-binding proteins, a novel class of proteins whose functional role may lie in helping influx of the sugar substrates.