FIG. 2.

(A) Screening of KH mutant Der proteins and their phenotypes in ΔrrmJ. The C-terminal part of the der gene was randomly mutagenized by PCR as described by Lerner et al. (18) and Spee et al. (25). The four deoxynucleoside triphosphates (dNTPs) (dATP, dCTP, dGTP, and dTTP) were depleted one at a time in PCR. MnCl₂ (0.5 mM) and dITP (200 μM) were also included in the reaction, and error-prone Taq polymerase was used. Plasmids with mutations were transformed into ΔrrmJ, and transformants were streaked onto LB plates containing ampicillin with or without 1 mM IPTG. (B) Growth curves of ΔrrmJ transformed with KH mutant plasmids. Cell culture and optical density measurement were carried out as described for Fig. 1B.