Introduction to the Q-mate™
Inducible Expression System
System for inducible gene expression in mammalian cells
- Controllable gene expression
- Tight regulation of transgenes
- Possibility to co-express GFP
- No transactivator required
- Rapid response after induction
- No pleiotropic effect on mammalian cells
The ability to regulate both the level and the duration of
gene expression permits the study of proteins whose constitutive
expression may not be tolerated by the host cell. Most
of the available inducible systems involve regulation by
heavy metals, steroid hormones, or heat shock. The limitation
of such inducible mammalian expression systems is the
pleiotropic effects that the inducers may exercise (heat
shock, glucocorticoids etc.).
Qbiogene has developed a new system for inducible gene
expression in mammalian cells: the Q-mate™ Inducible
Expression System. It is based on a prokaryotic regulatory system
adapted to construct inducible systems that function in
mammalian cells. Since prokaryotic inducer molecules usually do not have any target sites in mammalian cells, the possibility of interference with cellular processes is reduced.
The Q-mate™ CymR System
In the Q-mate™ CymR system, repression of gene expression
is mediated by the cumate repressor protein CymR bound to
operator sites in the absence of the inducer molecule cumate.
With cumate present, CymR binds to cumate and undergoes a
conformational change resulting in its release from the operator
sites. This permits transgene expression. The reporter construct
consists of three components: a strong promoter, the
CymR binding sites (cumate operator sequences, CuO), and a
reporter or a transgene (Figure 1).
The Q-mate™ CymR system makes use of the cym operon,
which in Pseudomonas putida F1 controls the expression of
genes intervening in the transformation of p-cymene (found in
volatile oils from several plant species) to p-cumate (Figure 2).
The cmt operon, located downstream of the cym operon, controls
the further degradation of the cumate molecule.
Upstream of the cym operon lies a regulatory gene, cymR,
encoding a 28-kDa repressor molecule (CymR), which monitors
expression of both the cym and cmt operons and is
induced by p-cumate. CymR is in a DNA-binding configuration
only in the absence of cymene and cumate.