title: FrnE, a cadmium-inducible protein in Deinococcus radiodurans, is characterized as a disulfide isomerase chaperone in vitro and for its role in oxidative stress tolerance in vivo.
abstract: Deinococcus radiodurans R1 exposed to a lethal dose of cadmium shows differential expression of a large number of genes, including frnE (drfrnE) and some of those involved in DNA repair and oxidative stress tolerance. The drfrnE::nptII mutant of D. radiodurans showed growth similar to that of the wild type, but its tolerance to 10 mM cadmium and 10 mM diamide decreased by ~15- and ~3-fold, respectively. These cells also showed nearly 6 times less resistance to gamma radiation at 12 kGy and ~2-fold-higher sensitivity to 40 mM hydrogen peroxide than the wild type. In trans expression of drFrnE increased cytotoxicity of dithiothreitol (DTT) in the dsbA mutant of Escherichia coli. Recombinant drFrnE showed disulfide isomerase activity and could maintain insulin in its reduced form in the presence of DTT. While an equimolar ratio of wild-type protein could protect malate dehydrogenase completely from thermal denaturation at 42 °C, the C22S mutant of drFrnE provided reduced protection to malate dehydrogenase from thermal inactivation. These results suggested that drFrnE is a protein disulfide isomerase in vitro and has a role in oxidative stress tolerance of D. radiodurans possibly by protecting the damaged cellular proteins from inactivation.
authors.affiliation: Radiation Research Division for Biotechnology, South Korea Atomic Energy Research Institute, Jeongeup, Republic of Korea.
authors.forename: Nivedita P
authors.initials: NP
authors.lastname: Khairnar
authors.forename: Min-Ho
authors.initials: MH
authors.lastname: Joe
authors.forename: H S
authors.initials: HS
authors.lastname: Misra
authors.forename: Sang-Yong
authors.initials: SY
authors.lastname: Lim
authors.forename: Dong-Ho
authors.initials: DH
authors.lastname: Kim
mesh_terms: D002104:Cadmium / Q000633:toxicity*; D004251:DNA Transposable Elements; D034301:Deinococcus / Q000187:drug effects / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005720:Gamma Rays; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D006861:Hydrogen Peroxide / Q000633:toxicity; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D018384:Oxidative Stress; D019704:Protein Disulfide-Isomerases / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological
chemical_list: D004251:DNA Transposable Elements; D018832:Molecular Chaperones; D002104:Cadmium; D006861:Hydrogen Peroxide; D019704:Protein Disulfide-Isomerases