Mismatch repair is diminished during stationary-phase mutation.
This paper is an invited Response to a recent Commentary [P.L. Foster, Rev. Mut. Res. 436 (1999) 179-184] entitled "Are adaptive mutations due to a decline in mismatch repair? The evidence is lacking". The Commentary argues that no evidence exists supporting the idea that mismatch repair is limiting specifically during stationary-phase mutation. A primary concern of the author is to question the method that we used previously to measure growth-dependent mutation. In this method, mutation rates are calculated using counts of mutant colonies taken at times when those colonies arise, rather than at a predetermined, fixed time. Here we show further data that illustrate why this must be done to ensure accurate mutation measurements. Such accuracy was necessary for our published determination that mismatch repair proteins are not limiting during growth-dependent mutation, but become so during stationary-phase mutation. We review the evidence supporting the idea that stationary-phase reversion of a lac frameshift mutation occurs in an environment of decreased mismatch repair capacity. Those data are substantial. The data presented in the Commentary, in apparent contradiction to this idea, do not justify the conclusion presented there.
Harris
R S
RS
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.
Feng
G
G
Ross
K J
KJ
Sidhu
R
R
Thulin
C
C
Longerich
S
S
Szigety
S K
SK
Hastings
P J
PJ
Winkler
M E
ME
Rosenberg
S M
SM
D000251:Adenosine Triphosphatases; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D020137:Base Pair Mismatch; D001483:Base Sequence; D002455:Cell Division; D004260:DNA Repair / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D007399:Interphase; D007763:Lac Operon; D008969:Molecular Sequence Data; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein; D009154:Mutation; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C074770:MutL protein, E coli; D000251:Adenosine Triphosphatases; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein; C497175:MutS protein, E coli