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RADIATION PROTECTION BY RECA PROTEIN IN PROCARYOTES AND NMAMMALIAN CELLS

Obiettivo

1.-MOLECULAR BASIS OF THE RADIATION PROTECTIVE EFFECT OF THE RECA PROTEIN.

2.-ANALOGS OF RECA PROTEIN IN YEAST AND MAMMALIAN CELLS.

3.-PROTEINS OTHER THAN RECA PROTEIN THAT PROTECT PROKARYOTES AS WELL AS EUKARYOTES AGAINST RADIATIONS.

4.-CHARACTERIZATION OF THE SOS SIGNAL PRODUCED BY RADIATION.
Antibodies raised against RecA protein of Escherichia coli have been used to identify proteins expressed by deoxyribonucleic acid (DNA) fragments of mouse embryos cloned into lambda gt11. 5 stable clones have been found, out of which 2, KIN2 and KIN17, have been sequenced. Both of these clones exhibited homologous sequences with the bacterial RecA protein, demonstrating that proteins involved in DNA transaction are common to procaryotes and eucaryotes. Isolation of the KIN polypeptide may help us to find the molecular basis of the SOS functions in mammalian cells and the mechanism of mutagenesis.
RADIATION PROTECTION BY RECA PROTEIN IN PROKARYOTES AND MAMMALIAN CELLS.
1.-MOLECULAR BASIS OF THE RADIATION PROTECTIVE EFFECT OF RECA PROTEIN
IT WAS ESTABLISHED BY THE RADIOBIOLOGY GROUP AT GIF THAT AMPLIFICATION OF RECA PROTEIN HAS A RADIOPROTECTIVE EFFECT ON THE SURVIVAL OF E.COLI. THE GROUP WILL NOW ISOLATE NWE MUTATED RECA PROTEINS IN ORDER TO DETERMINE THE DOMAINS OF THE MOLECULE THAT CONTROL RADIATION PROTECTION.

2.-ANALOGS OF RECA PROTEIN IN YEAST AND MAMMALIAN CELLS
RECENTLY, THE RADIOBIOLOGY GROUP HAS CHARACTERISED A MOLECULAR ANALOG OF RECA PROTEIN IN SACCHAROMYCES CEREVISIAE. AN ATTEMPT TO IDENTIFY AN ANALOG PROTEIN IN MOUSE CELLS 3T3 HAS ALSO BEEN SUCCESSFUL.
THE ANALYSIS WILL BE EXTENDED TO HUMAN CELLS SO AS TO DETERMINE THE SIMILARITY OF FUNCTIONS OF THE RECA LIKE PROTEINS IN EUKARYOTES. THE DNA SEQUENCES OF THE RECA GENES WILL BE DETERMINED AS WELL AS THE SIZE OF THE RECA PROTEINS.

3.-PROTEINS OTHER THAN RECA PROTEIN THAT PROTECT PROKARYOTES AS WELL AS EUKARYOTES AGAINST RADIATIONS.
IN THE PAST, THE RADIOBIOLOGY GROUP SHOWED THAT RADIOPROTECTION BY PLASMID PKM101, A DERIVATIVE OF PLASMID R46, ACTS BY A REPAIR MECHANISM DIFFERENT FROM THAT OF SOS REPAIR. DR BATTAGLIA AND ASSOCIATES RECENTLY DERIVED FROM THE NATURAL PLASMID R46 A NEW PLASMID, NAMED PR, WHICH PROTECTS E.COLI IN ADDITION TO THE PROTECTION PRODUCED BY AMPLIFICATION OF RECA PROTEIN. PLASMID MR POSSESSES ANOTHER PROPERTY: IT HAS A HIGH MUTAGENIC ACTIVITY.
PLASMID PR SEEMS TO HAVE THE ABILITY TO ENHANCE THE SURVIVAL OF MOUSE CELLS EXPOSED TO RADIATION.
IN SHORT, PLASMID PR SEEMS TO PROTECT PROKARYOTES AS WELL AS EUKARYOTES AGAINST THE DAMAGING EFFECTS OF UV-LIGHT. THE RADIOBIOLOGY GROUP PLANS TO INVESTIGATE THE MOLECULAR MECHANISM OF RADIOPROTECTION BY THIS PLASMID.

4.-CHARACTERIZATION OF THE SOS SIGNAL PRODUCED BY RADIATION.
THE RADIOBIOLOGY GROUP HAS CHARACTERIZED A POTENT SOS SIGNAL PRODUCED BY AN F REPLICON WHOSE REPLICATION WAS ABORTED BY IRRADIATION OR BY A CONDITIONAL GENETIC DEFECT.
THE GENES RESPONSIBLE FOR THE FORMATION OF THE SOS SIGNAL ARE BEING CHARACTERIZED AT THE GENETICAL AND BIOCHEMICAL LEVELS IN E.COLI. THEY CODE FOR TWO SMALL PROTEINS OF ABOUT 10 KDALTONS.
THE RADIOBIOLOGY GROUP IS INVESTIGATING THE ROLE OF THE RECBC NUCLEASE IN THE FORMATION OF THE SOS SIGNAL.

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CSC - Cost-sharing contracts

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Centre National de la Recherche Scientifique (CNRS)
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15 Quai Anatole France
75700 Paris
Francia

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