Escherichia coli SecG is required for residual export mediated by mutant signal sequences and for SecY-SecE complex stability.

ABSTRACT: Protein export to the bacterial periplasm is achieved by SecYEG, an inner membrane heterotrimer. SecY and SecE are encoded by essential genes, while SecG is not essential for growth under standard laboratory conditions. Using a quantitative and sensitive export assay, we show that SecG plays a critical role for the residual export mediated by mutant signal sequences; the magnitude of this effect is not proportional to the strength of the export defect. In contrast, export mediated by wild-type signal sequences is only barely retarded in the absence of SecG. When probed with mutant signal sequences, secG loss of function mutations display a phenotype opposite to that of prlA mutations in secY. The analysis of secG and prlA single and double mutant strains shows that the increased export con

SUBMITTER: Belin D 

PROVIDER: S-EPMC4285974 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature