In UV-irradiated Escherichia coli PQ35 overproducing the RecA protein, expression of the sfiA gene and dimer excision are alleviated.
Escherichia coli PQ35 cells carrying the sfiA-::lacZ operon fusion were transformed either with a multicopy plasmid containing the recA gene (pHSG262 recA) or with a multicopy plasmid alone (pHSG262). Both transformants were UV irradiated. Then induction of the sfiA gene and dimer excision were followed. Amplification of the recA gene partly inhibited both sfiA gene induction and dimer excision. The following interpretation of this phenomenon is proposed. When the RecA protein is in abundance, pyrimidine dimers are quickly masked by it. The masked dimers are less efficiently distinguished by excision nuclease and do not provide the induction signal. Due to this, induction of the sfiA gene as well as dimer excision are inhibited early.
Sedliaková
M
M
Cancer Research Institute, Slovak Academy of Sciences, Bratislava.
Masek
F
F
Kleibl
K
K
D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D003001:Cloning, Molecular; D004260:DNA Repair / Q000528:radiation effects; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D029968:Escherichia coli Proteins; D005784:Gene Amplification; D005786:Gene Expression Regulation / Q000528:radiation effects; D005798:Genes, Bacterial / Q000528:radiation effects*; D010957:Plasmids; D011938:Rec A Recombinases / Q000096:biosynthesis / Q000235:genetics*; D013014:SOS Response, Genetics / Q000528:radiation effects; D015533:Transcriptional Activation; D014170:Transformation, Genetic; D014466:Ultraviolet Rays
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C053139:sulA protein, E coli; D011938:Rec A Recombinases