Phosphorylation of Rrp2 at residue D52 is required for cell growth. (A) Diagram showing the generation of the conditional rrp2 mutant strain BbYP22, expressing Rrp2-D52A. The domain structure of Rrp2-D52A is shown below. (B) PCR analysis of BbYP22 (Rrp2-D52A mutant/pRrp2-HA). P1, P2, and P3 (Table 1), primers used to identify the strain BbYP22. P1 was at the same location shown in Fig. 2A. Lane 1, Rrp2-FL mutant/pRrp2-HA; lane 2, ΔRrp2 mutant/pRrp2-HA; lane 3, Rrp2-D52A mutant/pRrp2-HA; lane 4, PCR fragment 3 using P2 plus P3 digested with AfeI. (C) Immunoblot analysis of BbYP22. The lanes correspond to those in panel B. Bands corresponding to each protein are labeled on the right. Molecular masses are indicated on the left. (D) Growth curves of the Rrp2-FL mutant/pRrp2-HA and Rrp2-D52A mutant/pRrp2-HA strains grown for 6 days in the presence (50 μM) or absence (0 μM) of IPTG. The values in the growth curves represent the mean cell counts ± SD from three independent cultures.