Bio3400
Chapter 16
Regulation of Gene Expression in Prokaryotes
Prokaryotes respond to environmental conditions by regulating transcription via
,
, or
control.
In
E. coli
,
lactose
metabolism is
regulated
by
control of an
system,
where
is the inducer.
Expression of the
lac
operon is also subject to positive control: the operon is
by the catabolite-activating
protein
(CAP), together with Cyclic adenosine monophosphate (
cAMP
) when
is absent.
Binding of the repressor to the
forms a
loop
in the lac operon DNA.
The
E. coli
tryptophan (
trp
) operon is a
system
that is
repressed
by
of the
transcript.
Bacillus subtilis
uses a combination of
and
AT
proteins to regulate its
trp
operon via
.
The arabinose (a monosaccharide)
operon
is subject to both positive and negative regulation by the
protein.