Zinc is an essential micronutrient for mycobacteria, and its depletion induces multiple adaptive changes in cellular physiology, the most remarkable of which are remodeling and hibernation of ribosomes. Ribosome remodeling, induced upon relatively moderate depletion of zinc, involves replacement of multiple ribosomal proteins containing the zinc-binding CXXC motif (called C+ r proteins) by their motif-free C− paralogs. Severe zinc depletion induces binding of mycobacterial protein Y (Mpy) to the 70S C− ribosome, thereby stabilizing the ribosome in an inactive state that is also resistant to kanamycin and streptomycin. Because the Mpy binding region on the ribosome is proximal to the binding pocket of spectinamides (Spa), the preclinical drug candidates for tuberculosis, we addressed the impact of remodeling and hibernation of ribosomes on Spa sensitivity. We report here that while Mpy binding has no significant effect on Spa sensitivity to the ribosome, replacement of S14_C+ with its C− counterpart reduces the binding affinity of the drug by ∼2-fold, causing increased Spa tolerance in Mycobacterium smegmatis and Mycobacterium tuberculosis cells harboring the C− ribosome. The altered interaction between Spa and ribosomes likely results from new contact points for D67 and R83 residues of S14_C− with U1138 and C1184 of 16S rRNA helix 34, respectively. Given that M. tuberculosis induces ribosome remodeling during progression from the acute to chronic phase of lung infection, our findings highlight new considerations in the development of Spa as effective drugs against tuberculosis.

中文翻译：

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缺锌分枝杆菌核糖体中 S14 蛋白的替换可降低壮观酰胺敏感性


锌是分枝杆菌必需的微量营养素，其消耗会引起细胞生理学的多种适应性变化，其中最显着的是核糖体的重塑和冬眠。相对适度的锌消耗诱导的核糖体重塑涉及用不含基序的 C- 旁系同源物替换含有锌结合 CXXC 基序的多种核糖体蛋白（称为 C+ r 蛋白）。严重的锌耗尽会诱导分枝杆菌蛋白 Y (Mpy) 与 70S C− 核糖体结合，从而将核糖体稳定在非活性状态，同时对卡那霉素和链霉素具有抗性。由于核糖体上的 Mpy 结合区域靠近壮观酰胺 (Spa)（结核病临床前候选药物）的结合袋，因此我们研究了核糖体重塑和冬眠对 Spa 敏感性的影响。我们在此报告，虽然 Mpy 结合对 Spa 对核糖体的敏感性没有显着影响，但用 C− 对应物替换 S14 _C+会使药物的结合亲和力降低约 2 倍，导致耻垢分枝杆菌和结核分枝杆菌对 Spa 的耐受性增加含有 C− 核糖体的细胞。 Spa 和核糖体之间相互作用的改变可能是由于 S14 _C−的 D67 和 R83 残基分别与 16S rRNA 螺旋 34 的 U1138 和 C1184 的新接触点所致。鉴于结核分枝杆菌在肺部感染从急性期到慢性期的进展过程中诱导核糖体重塑，我们的研究结果强调了开发 Spa 作为有效抗结核药物的新考虑因素。