prlA-mediated suppression of signal sequence mutations is modulated by the secA gene product of Escherichia coli K-12

We studied the dependence of prlA-mediated suppression of signal sequence mutations in maltose-binding protein on cellular SecA levels in Escherichia coli. Reduction of SecA levels within the cell had strong positive and negative effects on prlA-mediated suppression, depending on the particular signal sequence mutations involved. This finding suggests that prlA and secA gene products are both components of a common export system.