MF7000839 Osmotically inducible protein C (Thermus thermophilus) 1ukk X-ray 1.60 Homodimer Thermus thermophilus 15111059 Rehse PH, Ohshima N, Nodake Y, Tahirov TH J. Mol. Biol. 2004 5 338 959-68 The X-ray crystallographic structure of osmotically inducible Protein C from the thermophilic bacterium, Thermus thermophilus HB8, was solved to 1.6A using the multiple wavelength anomalous dispersion method and a selenomethionine incorporated protein (Se-MAD). The crystal space group was P1 with cell dimensions of a=37.58 A, b=40.95 A, c=48.14 A, alpha=76.9 degrees, beta=74.0 degrees and gamma=64.1 degrees. The two tightly interacting monomers in the asymmetric unit are related by a non-crystallographic 2-fold. The dimer structure is defined primarily by two very long anti-parallel, over-lapping alpha-helices at the core, with a further six-stranded anti-parallel beta-sheet on the outside of the structure. With respect to the beta-sheets, both A and B monomers contribute three strands each resulting in an intertwining of the structure. The active site consists of two cysteine residues from one monomer and an arginine and glutamic acid from the other. Enzymatic assays have revealed that T.thermophilus OsmC has a hydroperoxide peroxidase activity. GO:0004601 peroxidase activity GO:0006979 response to oxidative stress 2 1 Homooligomeric enzymes Homodimeric enzymes All chains according to the most probable oligomerization state stored in PDBe were considered. A Osmotically inducible protein C Thermus thermophilus P84124 2 142 99% MPVRKAKAVWEGGLRQGKGVMELQSQAFQGPYSYPSRFEEGEGTNPEELIAAAHAGXFSMALAASLEREGFPPKRVSTEARVHLEVVDGKPTLTRIELLTEAEVPGISSEKFLEIAEAAKEGCPVSRALAGVKEVVLTARLV 142 secondary structure helix 24 27 secondary structure helix 34 39 secondary structure helix 45 69 secondary structure helix 108 120 secondary structure helix 123 129 secondary structure strand 3 11 secondary structure strand 18 23 secondary structure strand 28 33 secondary structure strand 75 85 secondary structure strand 92 103 secondary structure strand 134 141 pfam PF02566 OsmC-like protein 40 131 B Osmotically inducible protein C Thermus thermophilus P84124 2 142 99% MPVRKAKAVWEGGLRQGKGVMELQSQAFQGPYSYPSRFEEGEGTNPEELIAAAHAGXFSMALAASLEREGFPPKRVSTEARVHLEVVDGKPTLTRIELLTEAEVPGISSEKFLEIAEAAKEGCPVSRALAGVKEVVLTARLV 142 secondary structure helix 34 39 secondary structure helix 45 69 secondary structure helix 108 120 secondary structure helix 123 129 secondary structure strand 3 11 secondary structure strand 18 23 secondary structure strand 29 33 secondary structure strand 75 86 secondary structure strand 91 103 secondary structure strand 134 141 pfam PF02566 OsmC-like protein 40 131 Direct evidence The full structure participates in mutual synergistic folding. OsmC-like protein Ohr is a tightly folded homodimer with a large buried hydrophobic surface area. The two monomers are tightly wrapped around each other in a head-to-tail orientation. Dimerization is dominated by helix–helix packing interactions of two long helices at the center of the hydrophobic core of the dimeric enzyme. Also, each β-sheet is composed of six strands, three from one monomer and three from the other (beta sheet augmentation). The hydrophobic core, as well as the surrounding β-sheets, are generated by combining elements of both monomers, therefore, it is clear that the two polypeptide chains have to fold together to form active Ohr, and that each monomer would individually be unstable. The two active sites are also located at the dimer interface (PMID:12485986). A N/A B N/A MF7000837 MF7000838 MF7000839 MF7000840 MF7000841 MF7000842 MF7000843