Department of Chemistry, Indiana University, Bloomington, Indiana 47401, United States.
Department of Molecular Biosciences, University of Texas, Austin, Texas 78712, United States.
J Am Soc Mass Spectrom. 2024 Jun 5;35(6):1063-1068. doi: 10.1021/jasms.4c00080. Epub 2024 May 15.
Bortezomib, a small dipeptide-like molecule, is a proteasome inhibitor used widely in the treatment of myeloma and lymphoma. This molecule reacts with threonine side chains near the center of the 20S proteasome and disrupts proteostasis by blocking enzymatic sites that are responsible for protein degradation. In this work, we use novel mass-spectrometry-based techniques to examine the influence of bortezomib on the structures and stabilities of the 20S core particle. These studies indicate that bortezomib binding dramatically favors compact 20S structures (in which the axial gate is closed) over larger structures (in which the axial gate is open)─suppressing gate opening by factors of at least ∼400 to 1300 over the temperature range that is studied. Thus, bortezomib may also restrict degradation in the 20S proteasome by preventing substrates from entering the catalytic pore. That bortezomib influences structures at the entrance region of the pore at such a long distance (∼65 to 75 Å) from its binding sites raises a number of interesting biophysical issues.
硼替佐米是一种小分子二肽类似物，广泛用于治疗骨髓瘤和淋巴瘤。该分子与 20S 蛋白酶体中心附近的苏氨酸侧链反应，并通过阻断负责蛋白质降解的酶活性部位来破坏蛋白质的内稳态。在这项工作中，我们使用新型基于质谱的技术来研究硼替佐米对 20S 核心颗粒结构和稳定性的影响。这些研究表明，硼替佐米结合显著有利于紧凑的 20S 结构（其中轴向门关闭）而不是较大的结构（其中轴向门打开）-在研究的温度范围内，通过至少约 400 至 1300 的因子抑制门的打开。因此，硼替佐米也可能通过阻止底物进入催化孔来限制 20S 蛋白酶体中的降解。硼替佐米在距离其结合位点约 65 至 75Å 的位置影响孔入口区域的结构，这引发了许多有趣的生物物理问题。
