AnEscherichia coli curved DNA-binding protein whose expression is affected by the stationary phase-specific sigma factor σs

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Abstract
FromEscherichia coli, a DNA-binding protein that preferentially recognizes a curved DNA sequence was isolated and shown to correspond to one that has recently been reported as a binding protein for the replication origin of theE. coli chromosome, named Rob. Here, arob promoter-lacZ transcriptional fusion was constructed on the chromosome, and used to demonstrate that the expression ofrob is notably enhanced at the onset of stationary phase in Luria-broth and also under certain growth conditions in a minimal medium, such as glucose- and phosphate-starvation medium. It was further shown that this growth condition-dependent expression ofrob is notably reduced in a null mutant for the stationary phase-specific sigma subunit of RNA polymerase, σs, although σs-independent expression ofrob was significant during the logarithmic growth phase. Furthermore therob null mutant was found to exhibit, as compared with the wild-type, an altered profile of protein synthesis, particularly at the very late stationary phase.