Exploring Intein Inhibition by Platinum Compounds as an Antimicrobial Strategy
Exploring Intein Inhibition by Platinum Compounds as an Antimicrobial Strategy
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DOI：
10.1074/jbc.m116.747824
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发表时间：
2016-10-21
影响因子：
4.8
通讯作者：
Belfort, Marlene
中科院分区：
文献类型：
--
作者：
Chan, Hon;Pearson, C. Seth;Belfort, Marlene
内含子是一种自剪接蛋白元件，可以中断许多微生物中的基因和蛋白质，包括人类病原体结核分枝杆菌。在其N-端和C-端剪接连接处使用保守的催化亲核试剂，内含子能够从前体多肽中剔除。分枝杆菌重组酶RecA中内含子的剪接被广泛应用的抗癌药物顺铂(cis-[Pt(NH3)(2)Cl2])特异性地抑制，该化合物抑制分枝杆菌的生长。对铂(II)与RecA内含子结合的质谱学和结晶学研究表明，两个铂原子结合在N端和C端催化半胱氨酸残基上。对核磁共振光谱数据的动力学分析支持一种两步结合机制，即铂(II)首先在N末端快速可逆地相互作用，然后发生较慢的一级不可逆结合事件，涉及N和C末端。值得注意的是，化疗疗效和毒性所需的铂(II)化合物的配体不再与内联蛋白加合物中的金属原子结合。胺配体的缺乏和对磷化氢的需求是未来设计以内含子为目标的铂基化合物的跳板。由于内含子剪接机制在一系列病原微生物中是保守的，开发这些药物可能会导致新的、广泛的抗菌剂。
Inteins, self-splicing protein elements, interrupt genes and proteins in many microbes, including the human pathogen Mycobacterium tuberculosis. Using conserved catalytic nucleophiles at their N- and C-terminal splice junctions, inteins are able to excise out of precursor polypeptides. The splicing of the intein in the mycobacterial recombinase RecA is specifically inhibited by the widely used cancer therapeutic cisplatin, cis-[Pt(NH3)(2)Cl-2], and this compound inhibits mycobacterial growth. Mass spectrometric and crystallographic studies of Pt(II) binding to the RecA intein revealed a complex in which two platinum atoms bind at N- and C-terminal catalytic cysteine residues. Kinetic analyses of NMR spectroscopic data support a two-step binding mechanism in which a Pt(II) first rapidly interacts reversibly at the N terminus followed by a slower, first order irreversible binding event involving both the N and C termini. Notably, the ligands of Pt(II) compounds that are required for chemotherapeutic efficacy and toxicity are no longer bound to the metal atom in the intein adduct. The lack of ammine ligands and need for phosphine represent a springboard for future design of platinum-based compounds targeting inteins. Because the intein splicing mechanism is conserved across a range of pathogenic microbes, developing these drugs could lead to novel, broad range antimicrobial agents.