Figure 4.

Negative selection of HBP mutants with reduced binding to wild-type histone hairpin RNA. (Top) Positions of mutations. HBP is depicted as a bar with the minimal RBD shown in grey. Numbers indicate amino acid positions. The isolated mutants are indicated. Two identical mutants (R181C) were isolated independently. RR137/8AA and T171A were derived by site-directed mutagenesis and are marked with an asterisk. (Bottom) Summary of drop tests done with yeast expressing each of the mutant proteins together with wtHP as indicated. The bars indicate the maximal 3AT concentrations allowing for growth; 0 means no growth at 2.5 mM 3AT, which was the lowest 3AT concentration tested.