Exoenzyme Activity Of DrJAMM And Its Functions In Response To Oxidative Stress In Deinococcus Radiodurans

Deinococcus radiodurans is highly resistant to adverse external environment.It has a powerf?l antioxidant defense system and it is a model organism for scientists studying oxidative stress.In this paper,We took the dr₀402 gene and its encoded protein DrJAMM as the object to study the enzyme digestion activity of DrJAMM in vitro and DrJAMM 's role in the oxidative stress of the bacterium.The main res?lts are as follows:(1)Res?lts of bioinformatic analysis showed that DrJAMM is a typical JAMM/MPN metalloproteinase with a conserved JAMM domain,which may be related to the molybdenum cofactor(Moco)synthesis system together with DrMoaDMoaE(DR₂607)and DrMoe B(DR₂269)in Deinococcus radiodurans.DrJAMM protein has high homology with other JAMM proteins and it has m?ltiple conserved sites.The predicted metal binding sites Glu24,His83,His85 and Asp96 were highly conserved in organisms,and the predicted ?2-helix region(Pro61-Arg73)that interacting with the JAMM substrate protein is also conservative.It is likely that the predicted conserved sites and motifs play a key role in the activity of DrJAMM protein.(2)We successf?lly purified the wild type,point mutant,and truncated proteins of DrJAMM,as well as the DrMoaD-MoaE protein.We found that DrJAMM protein can cleave DrMoaD-MoaE into two fragments,and we also found that DrJAMM protein has a broad spectrum of metal ion selection,and the preference for Ca²⁺ and Mg²⁺.In addition,DrJAMM protein has a broad spectrum in the selection of digestion temperature,and is a protein that can play a stable role in digestion at 16? to 100?.The ?2-helix,E24,H85 and D96 sites of DrJAMM protein are important for the enzyme digestion activity of DrJAMM.(3)We successf?lly obtained three genetic mutatant by knock-out.The genetic mutatants are ? dr₀402,? dr₂607 and ? dr₂269.We found that ? dr₀402 was more sensitive to H₂O₂ than the wild-type strain,combined with the analysis of ROS scavenging ability and the comparison of protein expression levels in vivo,we concluded that dr₀402 was involved in the antioxidant stress of D.radiodurans.In addition,based on th res?lts of the changes of the genetic mutatants ' oxidation resistance,ROS removal ability,and the protein expression under the oxidative stress,we spec?late that DrJAMM protein participates in the Moco synthesis pathway,and then participates in the oxidative stress in the bacterium.We found that the activity of DMSO reductase in ?dr₀402 was almost completely lost and the DMSO reductase can respond to oxidative stress.Finally,we propose a model of DrJAMM participating in the oxidative stress resistance of D.radiodurans.DrJAMM participates in the Moco synthesis pathway of Deinococcus radiodurans,thereby inhibitorying the activity of DMSO reductase and ?ltimately participating in the oxidative stress of D.radioduran.This study provides clues and new ideas for the study of extreme resistance of D.radioduran,especially the mechanism of oxidative resistance.