Department of Chemistry, State University of New York at Albany, Albany, New York, United States of America.
PLoS One. 2013 Sep 10;8(9):e74576. doi: 10.1371/journal.pone.0074576. eCollection 2013.
The Mycobacterium tuberculosis proteasome is required for maximum virulence and to resist killing by the host immune system. The prokaryotic ubiquitin-like protein, Pup-GGE, targets proteins for proteasome-mediated degradation. We demonstrate that Pup-GGQ, a precursor of Pup-GGE, is not a substrate for proteasomal degradation. Using STINT-NMR, an in-cell NMR technique, we studied the interactions between Pup-GGQ, mycobacterial proteasomal ATPase, Mpa, and Mtb proteasome core particle (CP) inside a living cell at amino acid residue resolution. We showed that under in-cell conditions, in the absence of the proteasome CP, Pup-GGQ interacts with Mpa only weakly, primarily through its C-terminal region. When Mpa and non-stoichiometric amounts of proteasome CP are present, both the N-terminal and C-terminal regions of Pup-GGQ bind strongly to Mpa. This suggests a mechanism by which transient binding of Mpa to the proteasome CP controls the fate of Pup.
结核分枝杆菌蛋白酶体对于最大毒力和抵抗宿主免疫系统的杀伤至关重要。原核泛素样蛋白 Pup-GGE 可将蛋白质靶向蛋白酶体介导的降解。我们证明 Pup-GGQ（Pup-GGE 的前体）不是蛋白酶体降解的底物。使用 STINT-NMR 一种细胞内 NMR 技术，我们在活细胞内以氨基酸残基分辨率研究了 Pup-GGQ、分枝杆菌蛋白酶体 ATP 酶 Mpa 和 Mtb 蛋白酶体核心颗粒（CP）之间的相互作用。我们表明，在细胞内条件下，在没有蛋白酶体 CP 的情况下，Pup-GGQ 与 Mpa 的相互作用仅较弱，主要通过其 C 末端区域。当 Mpa 和非化学计量的蛋白酶体 CP 存在时，Pup-GGQ 的 N 末端和 C 末端区域都与 Mpa 结合紧密。这表明 Mpa 与蛋白酶体 CP 的瞬时结合控制 Pup 命运的机制。
