Structural insights into enzyme-substrate interaction and characterization of enzymatic intermediates of organic hydroperoxide resistance protein from Xylella fastidiosa.
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.
Oliveira
Marcos A
MA
Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo 05508-900, Brazil.
Guimarães
Beatriz G
BG
Cussiol
José R R
JR
Medrano
Francisco J
FJ
Gozzo
Fábio C
FC
Netto
Luis E S
LE
D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011092:Polyethylene Glycols / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D044167:Xylella / Q000737:chemistry / Q000201:enzymology
D001426:Bacterial Proteins; D005227:Fatty Acids; C112257:organic hydroperoxide resistance protein, Xanthomonas campestris; D011092:Polyethylene Glycols; D003545:Cysteine