Propionibacterium freudenreichii subsp. shermanii is known to prevent mutations caused by various agents such as N-methyl-N'-nitro-N-nitrosoguanidine, 9-aminoacridine, 4-nitro-quinoline-1-oxide and by UV radiation in both prokaryotic and eukaryotic cells. It was also shown to prevent or repair damage caused by H(2)O(2) or UV radiation in Salmonella typhimurium and Escherichia coli, a characteristic previously designated as reactivative effect. In order to characterise this effect at the molecular level, we have purified the active component from a P. freudenreichii cell-free extract using a combination of ammonium sulfate precipitation, anion-exchange and size-exclusion chromatography. The isolated 35 kDa protein was then identified using both N-terminal and internal peptide sequencing as a cysteine synthase. The latter was localised in the P. freudenreichii proteomic map. It is constitutively expressed but also clearly induced during adaptation to detergent and heat, but not acid, stresses. The biological meaning of cysteine synthase in the context of adaptation to oxidative and non-oxidative stresses is discussed.

No abstract

-A nucleoprotein complex (NPC) from P. sliennanii VKM-I 03 was purified to homogeneity by chromatography on OEAE-Sepharose FF and analysed by SOS-PAGE and HPLC. The NPC had a Mr of 44 kOa and exerted a protective and reactivating action on E. coli AB 1157, after treatment with different stresses including: heating, UV-irradiation" exposure to salts of heavy metals and ethanol. The cell-free extract, that served as the source of the NPC also showed a reactivating and protective effect in different pro-and eukaryotic organisms inactivated by different stress factors. Boiling the NPC for 2 min and treatment by pronase increased its UV -protective effect, butled to the loss of its reactivating effect. ln contrast, treatment with ONAse caused a marked decrease in the UV -protection property; RNAse had only a sm ail effect. © Inra/Elsevier, Paris.

No abstract

No abstract