Recombinant thioredoxin peroxidase from <i>Cryptosporidium parvum</i> has more powerful antioxidant activity than that from <i>Cryptosporidium muris</i>

다국어 초록 (Multilingual Abstract)

<P><B>Graphical abstract</B></P><P><ce:figure id='f0030'></ce:figure></P><P><B>Highlights</B></P><P>► Recombinant thioredoxin peroxidase of <I>Cryptosporidium parvum</I> and <I>Cryptosporidium muris</I> were expressed. ► Hydrogen peroxide consumption was greater in rCpTPx than in rCmTPx. ► Peroxidase activity of rCpTPx was highly enhanced by GSH, but that of rCmTPx was not. ► rCpTPx protected plasmid DNA from damage with only 12% of dose required with rCmTPx.</P> <P><B>Abstract</B></P><P><I>Cryptosporidium parvum</I> can survive exposure to harsh environmental conditions, various disinfectants, and high doses of γ-irradiation. In an animal study, more than 25kGy of γ-irradiation was necessary to eliminate <I>C. parvum</I> infectivity from mice. In contrast, <I>Cryptosporidium muris</I> (murine <I>Cryptosporidium</I>), which lives in stomach epithelium, lost its infectivity in mice with 1kGy of γ-irradiation. Recently, it was found that thioredoxin peroxidase was highly expressed in <I>C. parvum</I> oocysts irradiated with high doses of γ-irradiation. Therefore we hypothesize that antioxidant activity of the thioredoxin peroxidase is involved in the radioresistance of <I>C. parvum</I>. To verify this, thioredoxin peroxidases of <I>C. parvum</I> (CpTPx) and <I>C. muris</I> (CmTPx) were expressed in <I>Escherichia coli</I> cells, and their antioxidant activities were compared. Both CpTPx and CmTPx belong to the 2-Cys family of peroxiredoxins. Hydrogen peroxide consumption was approximately 2- to 12-fold greater in recombinant CpTPx (rCpTPx) than in recombinant CmTPx (rCmTPx) in the presence of 0.2mM dithioerythritol or glutathione (GSH), respectively. The peroxidase activity of rCpTPx was highly enhanced by GSH, but that of rCmTPx was not. The minimum dose of rCpTPx required to protect supercoiled plasmid DNA from damage by metal-catalyzed oxidation was only 12% of that required with rCmTPx. The results showed that rCpTPx has more powerful antioxidant activity than rCmTPx. Further investigations on the role of CpTPx in the radioresistance of <I>C. parvum</I> are warranted.</P>