REQUIMTE/CQFB, Dpto Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
Metallomics. 2012 Jan;4(1):16-22. doi: 10.1039/c1mt00124h. Epub 2011 Oct 19.
Although the number of papers about "vanadium" has doubled in the last decade, the studies about "vanadium and actin" are scarce. In the present review, the effects of vanadyl, vanadate and decavanadate on actin structure and function are compared. Decavanadate (51)V NMR signals, at -516 ppm, broadened and decreased in intensity upon actin titration, whereas no effects were observed for vanadate monomers, at -560 ppm. Decavanadate is the only species inducing actin cysteine oxidation and vanadyl formation, both processes being prevented by the natural ligand of the protein, ATP. Vanadyl titration with monomeric actin (G-actin), analysed by EPR spectroscopy, reveals a 1:1 binding stoichiometry and a K(d) of 7.5 μM(-1). Both decavanadate and vanadyl inhibited G-actin polymerization into actin filaments (F-actin), with a IC(50) of 68 and 300 μM, respectively, as analysed by light scattering assays, whereas no effects were detected for vanadate up to 2 mM. However, only vanadyl (up to 200 μM) induces 100% of G-actin intrinsic fluorescence quenching, whereas decavanadate shows an opposite effect, which suggests the presence of vanadyl high affinity actin binding sites. Decavanadate increases (2.6-fold) the actin hydrophobic surface, evaluated using the ANSA probe, whereas vanadyl decreases it (15%). Both vanadium species increased the ε-ATP exchange rate (k = 6.5 × 10(-3) s(-1) and 4.47 × 10(-3) s(-1) for decavanadate and vanadyl, respectively). Finally, (1)H NMR spectra of G-actin treated with 0.1 mM decavanadate clearly indicate that major alterations occur in protein structure, which are much less visible in the presence of ATP, confirming the preventive effect of the nucleotide on the decavanadate interaction with the protein. Putting it all together, it is suggested that actin, which is involved in many cellular processes, might be a potential target not only for decavanadate but above all for vanadyl. By affecting actin structure and function, vanadium can regulate many cellular processes of great physiological significance.
尽管过去十年中关于“钒”的论文数量增加了一倍，但关于“钒和肌动蛋白”的研究却很少。在本综述中，比较了钒氧、钒酸盐和十钒酸盐对肌动蛋白结构和功能的影响。钒氧（51）V NMR 信号在 -516 ppm 处变宽并强度降低，而钒酸盐单体（-560 ppm）则没有观察到这种影响。十钒酸盐是唯一诱导肌动蛋白半胱氨酸氧化和钒氧形成的物质，这两种过程都被该蛋白的天然配体 ATP 所阻止。用单体肌动蛋白（G-肌动蛋白）进行钒氧滴定，通过 EPR 光谱分析，发现 1:1 的结合化学计量比和 7.5 μM(-1)的 K(d)。十钒酸盐和钒氧都抑制 G-肌动蛋白聚合形成肌动蛋白丝（F-肌动蛋白），用光散射测定法分析，IC(50)分别为 68 和 300 μM，而钒酸盐在 2 mM 以下则没有检测到影响。然而，只有钒氧（高达 200 μM）会引起 G-肌动蛋白固有荧光的 100%猝灭，而十钒酸盐则显示出相反的效果，这表明存在钒氧高亲和力的肌动蛋白结合位点。十钒酸盐增加（2.6 倍）了肌动蛋白的疏水性表面，使用 ANSA 探针进行评估，而钒氧则降低了它（15%）。两种钒物种都增加了 ε-ATP 交换速率（k = 6.5 × 10(-3) s(-1)和 4.47 × 10(-3) s(-1)分别用于十钒酸盐和钒氧）。最后，用 0.1 mM 十钒酸盐处理的 G-肌动蛋白的 (1)H NMR 谱清楚地表明，蛋白质结构发生了重大变化，而在存在 ATP 时，这些变化则不太明显，这证实了核苷酸对十钒酸盐与蛋白质相互作用的预防作用。综上所述，肌动蛋白参与许多细胞过程，可能不仅是十钒酸盐，而且尤其是钒氧的潜在靶标。通过影响肌动蛋白的结构和功能，钒可以调节许多具有重要生理意义的细胞过程。
