3fdh

Protein Summary

Bacteroides thetaiotaomicron  protein BT_2033 (aka JCSG target 393011) is a member of a SusD/RagB family PF07980 of outer membrane nutrient receptors, and is homologous to two other recently solved JCSG structures (3ejn, 3cgh) and to the B. thetaiotamicron SusD (3ck7)). Exact function of BT_2033 is uknown, but it is likely to be involved in nutrient, most likely polysacharides, binding and utilization, as are all others Bacteroides SusD homologs. BT_2033 is likely to form a complex with its genomic neighbor, BT_2032, which is a SusC-homolog. SusC/SusD pairs are always conserved element of polysaccharide utilization loci (PULs) in Bacteroides. BT_2033/BT_2032 pair forms an unusually short PUL, containing only these two proteins.

A superposition of these structures are shown below [target (green), 3cgh (cyan), 3ejn (magenta)].

BT_2033 occurs as a monomer in the crystal structure, which is likely different from its biological form where it  probably forms a complex with its genomic neighbor, SusC homolog BT_2032, as do all known SusC/SusD pairs. It should be noted that the first 22 residues at the N-terminus, which form a membrane anchor, were omitted from the construct.

As other SusD homologs, BT_2033 consists of two domains, both helical. An N-terminal half of BT_2033 consists of several TRP-like repeats which support the helical, substrate binding C-terminal domain with a novel fold.

Ligand Summary