rho termination suppression=suppression by tRNA?

Russell A. Maurer ram3 at po.CWRU.Edu
Wed Nov 30 22:52:26 EST 1994


In a previous article, a () says:

>I am somewhat confused.  Is suppression of rho termination the same as
>suppression of a nonsense mutant by tRNA?
>
>king1 at uxa.cso.uiuc.edu
>
>Thanks
>

Let's get the basics clear first: suppressor tRNAs operate at the level of
translation, in contrast to "rho termination" which operates at the level
of transcription.  Now for the subtleties.  When translation terminates
prematurely due to a nonsense mutant, it often happens that transcription
ALSO terminates prematurely (but not precisely at the site of the nonsense
codon).  This is accounted for by rho termination factor's requirement for
a nice stretch of untranslated RNA as a place to engage the RNA.  This
effect of premature translation arrest on the fate of the message is called
polarity.  Introduction of a suppressor tRNA to suppress the translation
termination at the nonsense codon will also have the effect of suppressing
polarity.  Thus, my view is that suppression of translation termination and
suppression of transcription termination are distinct phenomena.  But they
often go together.

Hope this helps.

Russ Maurer



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