A new antioxidant with dual functions as a peroxidase and chaperone in Pseudomonas aeruginosa.
Thiol-based peroxiredoxins (Prxs) are conserved throughout all kingdoms. We have found that a conserved typical 2-Cys Prx-like protein (PaPrx) from Pseudomonas aeruginosa bacteria displays diversity in its structure and apparent molecular weight (MW), and can act alternatively as a peroxidase and molecular chaperone. We have also identified a regulatory factor involved in this structural and functional switching. Exposure of P. aeruginosa to hydrogen peroxide (H2O2) causes PaPrx to convert from a high MW (HMW) complex to a low MW (LMW) form, which triggers a chaperone to peroxidase functional switch. This structural switching is primarily guided by either the thioredoxin (Trx) or glutathione (GSH) systems. Furthermore, comparison of our structural data [native and non-reducing polyacrylamide gel electrophoresis (PAGE) analysis, size exclusion chromatography (SEC) analysis, and electron microscopy (EM) observations] and enzymatic analyses (peroxidase and chaperone assay) revealed that the formation of oligomeric HMW complex structures increased chaperone activity of PaPrx. These results suggest that multimerization of PaPrx complexes promotes chaperone activity, and dissociation of the complexes into LMW species enhances peroxidase activity. Thus, the dual functions of PaPrx are clearly associated with their ability to form distinct protein structures.
An
Byung Chull
BC
Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185, Korea.
Lee
Seung Sik
SS
Lee
Eun Mi
EM
Lee
Jae Taek
JT
Wi
Seung Gon
SG
Jung
Hyun Suk
HS
Park
Woojun
W
Chung
Byung Yeoup
BY
D000595:Amino Acid Sequence; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism*; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D008954:Models, Biological; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018384:Oxidative Stress; D009195:Peroxidase / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D020836:Protein Structure, Quaternary; D011550:Pseudomonas aeruginosa / Q000201:enzymology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D000975:Antioxidants; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D009195:Peroxidase