EFFECTS OF OVERPRODUCING THE UNIVERSAL STRESS PROTEIN, USPA, IN ESCHERICHIA-COLI K-12

A plasmid with the structural uspA gene under the control of a tac pro moter was used to study the effects of altering uspA expression levels under various growth conditions. We found that increasing UspA synthe sis to levels corresponding to physiologically induced levels decrease d the cell growth rate in minimal medium and reduced or abolished the cells' capacity to adapt to upshift conditions. As was demonstrated by two-dimensional gel electrophoresis, increased uspA expression caused global changes in the pattern of protein synthesis. In addition, elec trophoretic analysis together with V8 protease peptide mapping demonst rated that the pIs of some specific proteins became more acidic as a r esult of the elevation of the levels of UspA.