Gene expression - inducible Gene expression (Mar/08/2005 )

Inducible genes expressed only when induced or can express without induction also...? PLZ clarify . i have a E.coli clone and it is to be express after IPTG induction, but i found that it expresses without IPTG induction also.......but in less quantity. So plz expain it. i am little bit confused.

thanking in anticipation



CHANDRA

Hi Chandra,

You find with most inducible vectors there is a degree of promoter 'leakiness' allowing a basal level of gene expression. Apparently the RNA Polymerase can still bind although with considerably less afinity and generate transcripts. However, when IPTG is added this stabilises the RNA Polymerase complex and promotes the binding to the inducible promoter allowing transcripts to be run off. This promoter 'leakiness' can cause many problems if your gene is toxic to the e. coli. If this is a problem there are some vectors that demonstrate tighter regulation and absolutely require incubation with IPTG to induce expression and you could shop around for these.

Cheers,
Scott