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LEXSY Selection Guide: Which LEXSY should I use?

In vivo or in vitro:
The LEXSY protein expression technology is available as live cell-based expression system (In Vivo LEXSY) and as cell-free translation system (In Vitro LEXSY).
In Vivo LEXSY requires construction of an L. tarentolae expression strain that is suitable for fermentation in inexpensive media and that delivers high yields of recombinant proteins.
In Vitro LEXSY allows protein production directly from a gene of interest (either as a PCR product or sub-cloned into an appropriate DNA vector) which enables ultrafast production of a large number of proteins in parallel but which is not suitable for infinite upscale.

From gene to protein within approximately 6 weeksFrom gene to protein within 2 days or less
Scalable, suitable for production of large amounts of recombinant protein by cultivation in inexpensive mediaSmall scale protein preparation only
low costshigh costs

Constitutive or inducible:
In Vivo LEXSY is available in two principle configurations that are constitutive or inducible.

The constitutive system is the basic architecture which permits efficient production of a large variety of proteins. It is based on insertion of an expression cassette into the chromosomal ssu-locus. This cluster encodes the tandem 18S rRNA genes and is transcribed by the endogenous RNA Polymease I.

The inducible system enables tight control of protein expression, analogous to the well-known bacterial T7 RNA Polymerase/TET repressor architecture. Expression is switched on by addition of an inducer (tetracycline) and thereby alleviates potential toxicity issues of an expressed target protein.

ParametersConstitutive LEXSY
Inducible LEXSY
Typical cultivation time2-4 days2-4 days1-3 days1-3 days
Number of available selection
(1) 4 alternative selection antibiotics available (Nourseothricin (NTC), LEXSY Hygro, LEXSY Bleo, LEXSY Neo)
(2) 2 alternative selection antibiotics available (LEXSY Bleo, LEXSY Neo)

Furthermore, the inducible LEXSY is available as integrative or episomal version. In the integrative version the expression cassette is stably inserted into the chromosomal ornithin decarboxylase (odc) locus whereas the episomal version makes use of amplification and oligomerisation of expression plasmids maintained extrachromosomally as self-replicating episomes in L. tarentolae cells.

Finally, the inducible configuration termed pLEXSY_I-blecherry enables efficient screening of high expression clones and online monitoring of induction using Cherry-fluorescence. This was achieved by fusion of the ble resistance and cherry fluorescence genes.