Participation of Pur E Gene in Exoprotein Accumulation by a Protein-leaky Mutant of Escherichia coli

抄録

The genetic background of the protein-leaky mutant of Escherichia coli (PE4LA) was examined. This mutant preferentially excretes periplasmic proteins and outer membrane components. The results obtained from various crosses indicated that the mutation responsible for protein leakage was located near the purE gene. The amount of protein excreted decreased to about half whenever PE4LA was converted from Pur^- to Pur⁺ either by transduction or spontaneous reversion. When purine or pyrimidine auxotrophs were obtained from purE⁺ revertant of PE4LA, only auxotrophs whose blockages were located at a step identical or close to that governed by purE gene excreted proteins to the same extent as PE4LA. Excess adenine in the culture medium repressed exprotein accumulation by PE4LA. These results suggest that purE is involved in some way with protein excretion, and perhaps the accumulating metabolic intermediate(s) causes protein excretion due to a defect in purE enzyme.