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Inhibition of Protein Secretion by Cerulenin in Bacillus subtilis
Abstract
Cerulenin at a concentration of 10 g ml−1 only slightly inhibited growth of Bacillus subtilis YY88 while at 50μg ml−1 it inhibited the growth rate by 20–35% in complex media, and by 50–60% in mineral medium containing a single carbon source. Cerulenin (50μg ml−1) only partially prevented the secretion of α-amylase, proteases and levansucrase when added to bacteria growing in complex medium, but completely prevented the secretion of these enzymes in the mineral medium. Lower concentrations of cerulenin (10μg ml−1) inhibited the secretion of the enzymes in the mineral medium by up to 40%. When the cells were incubated with l-[35S]-methionine (plus a complete amino acid mixture) in the presence of cerulenin (50μg ml−1) protein secretion was lowered by 68%. Cerulenin inhibited translocation of membrane-bound forms of the secreted enzymes to 18% of the control value and the incorporation of radioactive methionine into membranes to 46%. These results suggest that the membrane-bound forms of secreted proteins play an important role in the secretion process in B. subtilis.
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© Society for General Microbiology, 1982