Selection for nonzero mutation rate

[bickle at urz.unibas.ch]

In article <4003 at fcs280s.ncifcrf.gov>, toms at fcs260c2.ncifcrf.gov (Tom Schneider) writes:
> Bacteriophage T4 DNA polymerase apparently has mutations which decrease the
> rate of mutation formation.  So mutation rate is under genetic control.  Sorry,
> I don't know a direct referece.
> 

The T4 DNA polymerase has mutations which work both ways: antimutators which
decrease mutation rates have either increased proof-reading 3'-5'
exonuclease activity or reduced affinity for the wrong precursors.
Mutators with *increased* mutation rates have, as I recall, a decreased
proof-reading activity.

See chapter 4 in DNA replication and mutagenesis (R.E. Moses and
W.C. Summers eds.) ASM 1988 ISBN 1-55581-003-9 for a reasonably recent 
review.

Tom Bickle
Dept of Microbiology
Biozentrum, Basel U.
Basel Switzerland