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. 2004 Jan 22;23(3):500–510. doi: 10.1038/sj.emboj.7600059

Figure 4.

Figure 4

A network of salt bridges important for Pre6 subunit occupation of the α3 position in pre9Δ proteasomes. (A) RasMol figures (PDB 1RYP) showing subunit interfaces. For the predicted interface between Pre8 and Pre6 in the pre9Δ proteasome (right panel), the Cα backbone of Pre6 was fitted onto the Pre9 structure. (B) Summary of key suppression tests with engineered complementary side-chain changes at Pre6 interfaces in the pre9Δ proteasome. Salt bridges are indicated by red lines and charge clashes by blue stars. (C) Suppression of the growth defect associated with pre9Δ pre6-K37E,D56K by pre8-K38E (see Figure 4Biii). The pre6 allele was on a high-copy (2μ) plasmid. MHY1603 cells expressing the indicated pRS425 plasmid-borne alleles were grown on FOA medium (30°C, 5 d) to evict the PRE6/URA3 plasmid originally present. (D) Suppressor analysis on FOA of pre9Δ pre6-K37E,D56KCEN and pre9Δ pre6-K37ECEN with high-copy (2μ) pre8-K38E and/or doa5-E60K. High-copy plasmid-borne alleles present (empty plasmids not listed): 1, pre8-K38E; 2, PRE8; 3, doa5-E60K; 4, DOA5; 5, pre8-K38E+doa5-E60K; 6, pre8-K38E+DOA5; 7, PRE8+doa5-E60K; 8, PRE8+DOA5; 9, none; 10, pre8-K38E; 11, PRE8; 12, doa5-E60K; 13, DOA5; 14, pre8-K38E+doa5-E60K; 15, none (*but carries PRE6, not pre6-K37E). 1–8, 30°C for 7 d; 9–15, 30°C for 4 d.