I have been evaluating the growth of two strains of E.coli BL21(DE3), one carrying a plasmid without peIB sequence and the same E.coli with the same plasmid but with peIB sequence inside the plasmid, under the same growth conditions. I have found that the strain with the pelB sequence, its growth rates are lower, of the order 0.1h-1, to what could this be due?
Thank you very much!
Is the PelB leader driving the secretion of some protein? There is much literature that says you can saturate the secretory system, so over expressing a protein with a leader sequence like PelB and cause problems because other proteins that must be secreted are unable to do so. This is even more true if the protein sequence attached to PelB is not secreted efficiently. You can even create situations of synthetic lethality in this way.
Michael J. Benedik Thanks for your answer Michael! yes, pelB leader is driving the secretion of the protein sfYFP into the periplasm.
Then your result is not necessarily surprising. If you think it might be a problem, then you could experiment with lower expression levels or growing at a reduced temperature.
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