I am currently trying to express human tyrosinase in E.coli and as you know this enzyme being a membrane protein it comes with a fair share of difficulties relating to expression in BL21(DE3). Literature shows that Lemo21 has been modified into a tunable expression system for difficult proteins, particularly membrane proteins. Now, From what i have read so far, as it turns out induction of protein expression in Lemo21 has been primarily IPTG. However, i am using the araBAD promoter vector system. Can i still use this Lemo21 for protein expression?
Hi there,
Lemo21(DE3) strain allows the fine tuning of T7 RNA polymerase expression through IPTG induction and rhamnose control of T7 lysozyme expression. These are absolutely useless to your expression vector which uses arabinose as inducer and therefore is fully independent of T7 system. For more details on Lemo21(DE3):
https://www.neb.com/-/media/nebus/files/application-notes/appnotec2528.pdf
Thank you for enlightening me on that. But what E. coli strain would be very useful for expressing membrane protein using the pBAD (araBAD) promoter system?
Hi again,
Unfortunately there is no specific strain designed and dedicated for arabinose induced production. You may however use the C41 or C43 derivatives of the BL21(DE3) strain made for IPTG induction of T7 RNA polymerase. These are basically strains which are less affected by membrane protein overexpression. For more info, you can read the following:
http://www.ibpc.fr/UMR7099/Publis/pdf/Hattab14-2.pdf
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