Figure 5. An in vivo transposition assay reveals a defect in the ability of TnsE^βMA mutants to activate transposition, and an increase in transposition frequency when β is over-expressed.

A. Transposition frequency is reduced significantly below wild-type with each of the six TnsE^βMA mutations. Transposition was monitored in cells expressing TnsABC and wild type TnsE or a mutant TnsE containing an alanine substitution at one of six positions in the putative β clamp interacting motif (see text for details). A western blot using an anti-TnsE antibody is displayed below the graph. Transposition assays were conducted in recA⁻ cells containing tns genes on plasmids using a lambda delivery vector (McKown et al., 1988). Error bars indicate the standard error of the mean (n=3).

B. Over-expression of β results in a significant increase in TnsE-mediated transposition. Transposition was monitored in cells expressing TnsABC+E with a plasmid expressing β or an empty vector. Error bars indicate standard error of the mean (n=3).