F. Tesfaselase et Wt. Drabble, SPECIFIC BINDING OF DNAA PROTEIN TO A DNAA BOX IN THE GUAB GENE OF ESCHERICHIA-COLI K12, European journal of biochemistry, 241(2), 1996, pp. 411-416
Expression of the guaBA operon of Escherichia coli is regulated by the
DNA replication-initiating protein, DnaA. Two DnaA boxes, which are p
otential binding sites for DnaA, are present in the gun operon. One bo
x (with 8/9 match to the DnaA box consensus sequence) is at the gua pr
omoter; the other box, which has a consensus sequence, is on the non-t
ranscribed strand within the guaB coding region approximately 200 bp d
ownstream of the initiation codon. The binding in vitro of purified Dn
aA protein to these boxes was investigated by filter retention and gel
retardation analysis, and by deoxyribonuclease I footprinting, using
restriction fragments of gun operon DNA. DnaA protein was shown to bin
d specifically only to the fragment carrying the consensus sequence Dn
aA box, and to protect this box from deoxyribonuclease I. Transcriptio
n termination resulting from the binding of DnaA to this box within th
e guaB gene explains repression by DnaA of the gun operon in vivo.