FIG 2.
The C-terminal 28 residues regulate E1 hexamer formation. (A) Cartoon showing the sequence of the C-terminal module with deletions and point mutations in the context of E308–605. (B) The deletion mutants in the C-terminal module were tested for hexamer formation in the context of E1308–605 using an ssDNA probe. Two, 4, and 8 ng each of the proteins E1308–577, E1308–584, E1308–589, E1308–592, E1308–597, E1308–600, and E1308–605 were incubated with a 41-mer ssDNA probe (∼2 fmol) in the presence of ADP and tested for hexamer formation by EMSA. The migration of the E1 hexamer is indicated. (C) Two, 4, and 8 ng each of the proteins with point mutations G588A, F594A, and C596A and the deletion mutants E1308–577 7×A and E1308–577 7×N were incubated with a 41-mer ssDNA probe in the presence of ADP and tested for hexamer formation by EMSA. (D) One hundred micrograms of E1308–592 was sedimented in a 5 to 30% glycerol gradient. The protein was detected by Bradford assays and its sedimentation was compared to that of the marker proteins carbonic anhydrase and bovine serum albumin (BSA).