title: Expression of Escherichia coli cspA during early exponential growth at 37 °C.
abstract: CspA is a small (7.4 kDa) nucleic acid binding protein of Escherichia coli whose expression is stimulated after cold-stress but whose level is also extraordinarily high during the early phase of growth of non-stressed cells. In this study the relationship existing between cspA transcription/translation on the one hand and the acquisition of critical mass for cell division and chromosome replication, on the other, in stationary phase cells subjected to a nutritional up-shift at 37 °C has been analyzed. Measurements of optical density and viable counts, pulse-chase, real-time PCR and immunodetection experiments, as well as cytofluorimetric and DNA duplication analyses show that synthesis of new CspA molecules at 37 °C is not only restricted to the lag phase ensuing the nutritional up-shift, but continues also during the first stages of logarithmic growth, when cells have already started dividing; although the early synthesized molecules are diluted by the following cell divisions and new synthesis occurs at an extremely low level, cspA mRNA and CspA continue to be present. A possible explanation for the apparent paradox that cspA is activated not only following cold stress, but also under non-stress and other stress conditions which entail a down-regulation of bulk gene expression and protein synthesis is presented.
authors.affiliation: Laboratory of Genetics, School of Biosciences and Biotechnology, University of Camerino, 62032 Camerino, Italy. anna.brandi@unicam.it
authors.forename: Anna
authors.initials: A
authors.lastname: Brandi
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Pon
mesh_terms: D002455:Cell Division; D057773:Cold Shock Proteins and Peptides; D004926:Escherichia coli / Q000254:growth & development* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D006358:Hot Temperature; D014176:Protein Biosynthesis; D055550:Protein Stability
chemical_list: D057773:Cold Shock Proteins and Peptides; C498192:CspA protein, E coli; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins