In: Biology
What does the lac repressor protein from bacteria have in common with the Gal4 protein from yeast?
Thus in simple terms both the lac repressor protein from
bacteria and Gal4 protein from yeast both act as repressor when
considering the bacterial cell. The lac repressor operator system
can be replaced functionally by a eukaryotic DNA-binding protein
and its DNA recognition site. the gal4 protein made in E.coli
acquires a conformation that permits rather specific DNA
recognition on the chromosome of E. coli. Even though in yeast this
protein is a positive transcription activator, in E. coli
under
these circumstances it can act as a repressor.
Here the binding of a gal4 protein dimer to the target DNA that
overlaps the transcription initiation site will inhibit
transcription
by a mechanism similar to that of the lac repressor.The gal4
protein is high enough to achieve a repression rate of at
least
30-fold after the induction of gal4 synthesis. The inhibition of
bacterial growth after induction suggests that other sequences on
the chromosome may be recognized by the
gal4 protein, which thereby interferes with the expression of one
or more essential bacterial genes.