LEVELS OF THE VSR ENDONUCLEASE DO NOT REGULATE STATIONARY-PHASE REVERSION OF A LAC(-) FRAMESHIFT ALLELE IN ESCHERICHIA-COLI

Vsr endonuclease, which initiates very short patch repair, has been hy pothesized to regulate mutation in stationary-phase cells. Overexpress ion of Vsr does dramatically increase the stationary-phase reversion o f a Lac(-) frameshift allele, but the absence of Vsr has no effect. Th us, at least in this case, Vsr has no regulatory role in stationary-ph ase mutation, and the effects of Vsr overproduction are likely to be a rtifactual.