Year-end Sale % OFF 
Abstract
Peroxiredoxin Q (PrxQ) that belonged to the cysteine-based peroxidases has long been identified in numerous bacteria, but the information on the physiological and biochemical functions of PrxQ remain largely lacking in Corynebacterium glutamicum. To better systematically understand PrxQ, we reported that PrxQ from model and important industrial organism C. glutamicum, encoded by the gene ncgl2403 annotated as a putative PrxQ, played important roles in adverse stress resistance. The lack of C. glutamicum prxQ gene resulted in enhanced cell sensitivity, increased ROS accumulation, and elevated protein carbonylation levels under adverse stress conditions. Accordingly, PrxQ-mediated resistance to adverse stresses mainly relied on the degradation of ROS. The physiological roles of PrxQ in resistance to adverse stresses were corroborated by its induced expression under adverse stresses, regulated directly by the stress-responsive ECF-sigma factor SigH. Through catalytical kinetic activity, heterodimer formation, and bacterial two-hybrid analysis, we proved that C. glutamicum PrxQ catalytically eliminated peroxides by exclusively receiving electrons from thioredoxin (Trx)/thioredoxin reductase (TrxR) system and had a broad range of oxidizing substrates, but a better efficiency for peroxynitrite and cumene hydroperoxide (CHP). Site-directed mutagenesis confirmed that the conserved Cys49 and Cys54 are the peroxide oxidation site and the resolving Cys residue, respectively. It was also discovered that C. glutamicum PrxQ mainly existed in monomer whether under its native state or functional state. Based on these results, a catalytic model of PrxQ is being proposed. Moreover, our result that C. glutamicum PrxQ can prevent the damaging effects of adverse stresses by acting as thioredoxin-dependent monomeric peroxidase could be further applied to improve the survival ability and robustness of the important bacterium during fermentation process.
Highlights
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are highly active compounds that are unavoidably generated during normal cell metabolism and overdone under adverse conditions
To determine the oligomeric form exhibited by C. glutamicum Peroxiredoxin Q (PrxQ), it was expressed in E. coli BL21 (DE3), purified by homogeneity, and cleaved with Enterokinase-Max to remove His6 tag
According to the number of conserved cysteine residues directly involved in catalysis, Prxs are classified into three types and six subgroups: typical 2-Cys (Prx1), atypical 2-Cys (Tpx, PrxQ, and Prx5), and 1-Cys Prxs (Prx6 and AhpE) [9,10,11]
Summary
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are highly active compounds that are unavoidably generated during normal cell metabolism and overdone under adverse conditions. Based on abundant sequence homology and structural similarity analyses, they have been divided into six subfamilies: AhpC/Prx, Prx, Prx, Tpx, PrxQ-BCP, and AhpE [5,6,7,8] They can be classified into three types according to their distinct catalytic mechanisms: typical 2-Cys (Prx and AhpC), atypical 2-Cys (Tpx, PrxQ, and Prx5), and 1-Cys Prxs (Prx and AhpE) [9,10,11]. To regenerate the active form of Prx and go on another catalytic cycle, the Cys-sulfenic acid (CP-SOH) must be reduced to a thiol and recycled to the CP. PrxQs usually exists only in monomeric state with an intramolecular disulfide bond between two Cys residues separated by only four amino acids and were reduced by Trx [15]. Currently existing results are contradictory, unilateral, and unsystematic, which makes PrxQ deserve to be further studied
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
