Structure of OsmC from Escherichia coli: a salt-shock-induced protein.

The crystal structure of an osmotically inducible protein (OsmC) from Escherichia coli has been determined at 2.4 A resolution. OsmC is a representative protein of the OsmC sequence family, which is composed of three sequence subfamilies. The structure of OsmC provides a view of a salt-shock-induced protein. Two identical monomers form a cylindrically shaped dimer in which six helices are located on the inside and two six-stranded beta-sheets wrap around these helices. Structural comparison suggests that the OsmC sequence family has a peroxiredoxin function and has a unique structure compared with other peroxiredoxin families. A detailed analysis of structures and sequence comparisons in the OsmC sequence family revealed that each subfamily has unique motifs. In addition, the molecular function of the OsmC sequence family is discussed based on structural comparisons among the subfamily members.