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SeqA, the Escherichia coli origin sequestration protein, is also a specific transcription factor
Author(s) -
Słomińska Monika,
Węgrzyn Alicja,
Konopa Grażyna,
Skarstad Kirsten,
Węgrzyn Grzegorz
Publication year - 2001
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2001.02480.x
Subject(s) - biology , escherichia coli , transcription factor , genetics , transcription (linguistics) , computational biology , microbiology and biotechnology , gene , linguistics , philosophy
The SeqA protein is a negative regulator of initiation of DNA replication in the Escherichia coli chromosome. Here, we demonstrate that SeqA stimulates transcription from the bacteriophage λ p R promoter both in vivo and in vitro . The activity of the λ p L promoter was found not to be affected by this protein. SeqA‐mediated stimulation of p R was dependent on the state of template methylation: transcription was activated on fully methylated and hemimethylated templates but not on an unmethylated template. Using electrophoretic mobility shift assay and electron microscopy, we demonstrated that SeqA interacts specifically with a p R promoter region located on both fully methylated and hemimethylated DNA molecules, but not on unmethylated DNA. The activity of SeqA was found to affect the initiation of λ plasmid replication positively in vivo , probably via p R ‐dependent expression of λ replication genes and transcriptional activation of ori λ. We conclude that, apart from its function in the control of DNA replication, SeqA is also a specific transcription factor.