MF7000840 Peroxide resistance protein (Xylella fastidiosa) 1zb8 X-ray 2.40 Homodimer Xylella fastidiosa 16631787 Oliveira MA, Guimarães BG, Cussiol JR, Medrano FJ, Gozzo FC, Netto LE J. Mol. Biol. 2006 2 359 433-45 Organic hydroperoxide resistance proteins (Ohr) belong to a family of proteins that possess thiol-dependent peroxidase activity endowed by reactive cysteine residues able to reduce peroxides. The crystal structure of Ohr from Xylella fastidiosa in complex with polyethylene glycol, providing insights into enzyme-substrate interactions is described herein. In addition, crystallographic studies, molecular modeling and biochemical assays also indicated that peroxides derived from long chain fatty acids could be the biological substrates of Ohr. Because different oxidation states of the reactive cysteine were present in the Ohr structures from X. fastidiosa, Pseudomonas aeruginosa and Deinococcus radiodurans it was possible to envisage a set of snapshots along the coordinate of the enzyme-catalyzed reaction. The redox intermediates of X. fastidiosa Ohr observed in the crystals were further characterized in solution by electrospray ionization mass spectrometry and by biochemical approaches. In this study, the formation of an intramolecular disulfide bond and oxidative inactivation through the formation of a sulfonic acid derivative was unequivocally demonstrated for the first time. Because Ohr proteins are exclusively present in bacteria, they may represent promising targets for therapeutical drugs. In this regard, the structural and functional analyses of Ohr presented here might be very useful. 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 Organic hydroperoxide resistance protein Xylella fastidiosa Q9PCF4 3 143 98% MNSLEKVLYTAIVTATGGRDGSVVSSDNVLNVKLSVPQGLGGPGGSGTNPEQLFAAGYSACFIGALKFVANKEKVDLPAEPRVEGRVGIGEIPGGFGLVVELRIAVSGMERSMLQTLVDKAHRVCPYSNATRGNIDVVLILID 143 secondary structure helix 37 41 secondary structure helix 49 73 secondary structure helix 110 125 secondary structure helix 125 132 secondary structure strand 9 16 secondary structure strand 21 25 secondary structure strand 31 34 secondary structure strand 82 92 secondary structure strand 95 105 secondary structure strand 137 141 pfam PF02566 OsmC-like protein 44 137 B Organic hydroperoxide resistance protein Xylella fastidiosa Q9PCF4 3 143 98% MNSLEKVLYTAIVTATGGRDGSVVSSDNVLNVKLSVPQGLGGPGGSGTNPEQLFAAGYSACFIGALKFVANKEKVDLPAEPRVEGRVGIGEIPGGFGLVVELRIAVSGMERSMLQTLVDKAHRVCPYSNATRGNIDVVLILID 143 secondary structure helix 37 41 secondary structure helix 49 73 secondary structure helix 110 125 secondary structure helix 125 132 secondary structure strand 9 16 secondary structure strand 22 25 secondary structure strand 31 33 secondary structure strand 82 92 secondary structure strand 95 105 secondary structure strand 137 142 pfam PF02566 OsmC-like protein 44 137 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