DNA and errors

Mike Marr mtm5 at cornell.edu
Mon Feb 9 16:12:41 EST 1998


Jay Mone' wrote:
> 
> Rob,
> DNA polymerase has an inherent error rate of approximately 10-8, while
> RNA polymerase has an error rate of approx. 10-4.  A large part of the
> difference is due to the lack of prrofreading ability by RNA pol.  DNA
> pol has the ability to check newly synthesized DNA.  If the DNA pol
> detects an error, it can back track, excise the error, and correct it.
> RNA pol lacks this ability.
> 
> Jay Mone'

Do you have a reference for those RNAP numbers? Is that a single subunit
RNAP Like T7, SP6 or T3 or a multi subunit RNAP like PolII or E.coli
RNAP. The multisubunit RNAPs have mechanisms for cleaving incorrect or
mismatched RNA. The model says that the polymerase rolls backwards and
uses its active site to cleave off a small bit of RNA then it can
continue with synthesis. There are factors required for this action to
occur efficiently; in E. coli GreA or GreB, in PolII S1, elongin, TFIIS
and possibly others.

MTM



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