Most eukaryotic peroxiredoxins (Prxs) are readily inactivated by a high concentration of hydrogen peroxide (H2O2) during catalysis owing to their “GGLG” and “YF” motifs. However, such oxidative stress sensitive motifs were not found in the previously identified filamentous fungal Prxs. Additionally, the information on filamentous fungal Prxs is limited and fragmentary. Herein, we cloned and gained insight into Aspergillus nidulans Prx (An.PrxA) in the aspects of protein properties, catalysis characteristics, and especially H2O2 tolerability. Our results indicated that An.PrxA belongs to the newly defined family of typical 2-Cys Prxs with a marked characteristic that the “resolving” cysteine (CR) is invertedly located preceding the “peroxidatic” cysteine (CP) in amino acid sequences. The inverted arrangement of CR and CP can only be found among some yeast, bacterial, and filamentous fungal deduced Prxs. The most surprising characteristic of An.PrxA is its extraordinary ability to resist inactivation by extremely high concentrations of H2O2, even that approaching 600 mM. By screening the H2O2- inactivation effects on the components of Prx systems, including Trx, Trx reductase (TrxR), and Prx, we ultimately determined that it is the robust filamentous fungal TrxR rather than Trx and Prx that is responsible for the extreme H2O2 tolerence of the An.PrxA system. This is the first investigation on the effect of the electron donor partner in the H2O2 tolerability of the Prx system.
Bibliographical noteFunding Information:
This work was sponsored by the National Natural Science Foundation of China (21672065, 21636003, and 31471659), the Shanghai Pujiang Program (16PJ1402500), and the National Special Fund for State Key Laboratory of Bioreactor Engineering (Grant No. 2060204).
- Filamentous fungus
- Hydrogen peroxide
- Oxidative stress
- Thioredoxin reductase