Fig. 6.

The rpd3Δ cells show increased acetylation of Sgf73 on lysine 33. A, MS and MS/MS spectra of Sgf73 peptide containing acetylated lysine 33. The MS spectrum shows increased intensity of the peptide in rpd3Δ cells compared with wild-type control cells, and the fragment spectrum supports the peptide sequence identification and localization of the acetyl group on the indicated lysine. B, Lysine 33 of Sgf73 is located at the interaction interface of Sgf73 and Ubp8. The left panel shows cocrystal structure of Sgf73 and Ubp8 demonstrating a role of the K33 side chain in forming a hydrogen bond with the side chain of Q62 of Ubp8. The right panel shows a snapshot from the MD simulations, indicating that acetylation of Sgf73 within the WK motif at K33 neutralizes its positive charge, and moves it away from Upb8 Q62 side chain, with potential to weaken the interaction between Sgf73 and Ubp8.