OVEREXPRESSION OF PHOSPHATIDYLGLYCEROPHOSPHATE SYNTHASE RESTORES PROTEIN TRANSLOCATION IN A SECG DELETION MUTANT OF ESCHERICHIA-COLI AT LOW-TEMPERATURE

The E. coli secG deletion mutant is unable to grow and is defective in protein translocation at low temperature, A gene of Bacillus subtilis , which is able to restore the growth of the deletion mutant at low te mperature, was found as a multi-copy suppressor, Sequencing of this ge ne revealed significant homology to E. coli pgsA, which encodes phosph atidylglycerophosphate synthase, an enzyme involved in acidic phosphol ipid synthesis, A plasmid carrying E. coli pgsA also restored the grow th of the deletion mutant. Furthermore, protein translocation in the d eletion mutant was stimulated when it harbored a plasmid carrying pgsA , A possible mechanism underlying the pgsA-dependent suppression of th e secG deletion mutation is discussed.