TnPhoA mutagenesis question
rafael at howard.genetics.utah.edu
Wed Aug 30 13:37:33 EST 1995
On Tue, 29 Aug 1995 cliff at molbiol.uct.ac.za wrote:
> My question is - does this mean that the fda gene
> downstream of pgk is automatically inactive (polar mutation) OR does
> TnphoA (or Tn5 for that matter) have a known endogenous promoter in its
> inverted repeats ie. will the fda gene be transcribed from within the
> transposon ?
Normally, yes. Tn's normally create polar mutations. Some transposons
have those out promoters, but I think Tn5 does not have any. Any
transponible elements book could give you that information.
Anyway, you may consider internal promoters, very common in some
operons; even a promoter can be created after the insertion, combining
sequences from the Tn and the target. Also, polar mutations depends on
rho-dependent termination spots. So there are some situations when the
insertions are not polar, but they are pretty infrequent.
Rafael Maldonado | La cita ha sido
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