Substitution of UmuD' for UmuD does not affect SOS mutagenesis.
In order to study the role of UmuDC proteins in SOS mutagenesis, we have constructed new Escherichia coli K-12 strains to avoid i) over-production of Umu proteins, ii) the formation of unwanted mixed plasmid and chromosomal Umu proteins upon complementation. We inserted a mini-kan transposon into the umuD gene carried on a plasmid. The insertion at codon 24 ends protein translation and has a polar effect on the expression of the downstream umuC gene. We transferred umuD24 mutation to the E coli chromosome. In parallel, we subcloned umuD+ umuC+ or umuD' umuC+ genes into pSC101, a low copy number plasmid. In a host with the chromosomal umuD24 mutation, plasmids umuD+ umuC+ or umuD' umuC+ produced elevated resistance to UV light and increased SOS mutagenesis related to a gene dosage of about 3. UV mutagenesis was as high in umuD' umuC+ hosts devoid of UmuD+ protein as in umuD+ umuC+ hosts. UmuD' protein, the maturated form of UmuD, can substitute for UmuD in SOS mutagenesis.
Bailone
A
A
Groupe d'Etude Mutagénèse et Cancérogénèse, Laboratoire d'Enzymologie, CNRS, Gif-sur-Yvette, France.
Sommer
S
S
Knezević
J
J
Devoret
R
R
D001426:Bacterial Proteins / Q000235:genetics*; D003062:Codon; D004259:DNA-Directed DNA Polymerase; D004926:Escherichia coli / Q000235:genetics* / Q000528:radiation effects; D029968:Escherichia coli Proteins; D015870:Gene Expression / Q000528:radiation effects; D005798:Genes, Bacterial / Q000528:radiation effects; D016254:Mutagenesis, Insertional; D010957:Plasmids; D014176:Protein Biosynthesis; D013014:SOS Response, Genetics / Q000528:radiation effects; D014466:Ultraviolet Rays
D001426:Bacterial Proteins; D003062:Codon; D029968:Escherichia coli Proteins; D004259:DNA-Directed DNA Polymerase; C055218:UmuD protein, E coli