Bacillus subtilis alpha-amylase: the rate limiting step of secretion is growth phase-independent.
When Bacillus subtilis alpha-amylase was expressed under the control of sacR in a degU32(Hy) strain, the production of exoenzyme occurred during both the exponential and stationary phases of growth. In each phase, pulse-chase experiments showed that the rate-limiting step of the secretion process was the release of the processed form of the protein in each physiological context. The rate of this event was slightly slower (t(1/2) = 3.2 min) during the stationary phase than during the exponential phase (t(1/2) = 2 min). The effectors which possibly control the efficiency of the release stage, the level of PrsA or the calcium binding properties of the cell wall, remained unchanged throughout growth phases.
Institut Jacques Monod-C.N.R.S, Universités Paris, France.
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E
Haddaoui
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R
Chambert
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MF
Petit-Glatron
O
O
Lindy
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M
Sarvas
D001412:Bacillus subtilis / Q000201:enzymology* / Q000254:growth & development; D001426:Bacterial Proteins; D002118:Calcium / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D007700:Kinetics; D008074:Lipoproteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D000516:alpha-Amylases / Q000096:biosynthesis / Q000378:metabolism*
D001426:Bacterial Proteins; D008074:Lipoproteins; D008565:Membrane Proteins; C082160:prsA protein, bacteria; D000516:alpha-Amylases; D002118:Calcium