Interaction of Vanadium(IV) Species with Ubiquitin: A Combined Instrumental and Computational Approach

Abstract

The interaction of VIVO2+ ion and five VIVOL2 compounds with potential pharmacological application, where L indicates maltolate (ma), kojate (koj), acetylacetonate (acac), 1,2-dimethyl-3-hydroxy-4­(1H)-pyridinonate (dhp), and l-mimosinate (mim), with ubiquitin (Ub) was studied by EPR, ESI-MS, and computational (docking and DFT) methods. The free metal ion VIVO2+ interacts with Glu, Asp, His, Thr, and Leu residues, but the most stable sites (named 1 and 2) involve the coordination of (Glu16, Glu18) and (Glu24, Asp52). In the system with VIVOL2 compounds, the type of binding depends on the vanadium concentration. When the concentration is in the mM range, the binding occurs with cis-VOL2(H2O), L = ma, koj, dhp, and mim, or with VO­(acac)2: in the first case, the equatorial coordination of His68, Glu16, Glu18, or Asp21 residues yields species with formula n[VOL2]–Ub where n = 2–3, while with VO­(acac)2 only noncovalent surface interactions are revealed. When the concentration of V is on the order of micromolar, the mono-chelated species VOL­(H2O)2 + with L = ma, koj, acac, dhp, and mim, favored by the hydrolysis, interact with Ub, and adducts with composition n[VOL]–Ub (n = 1–2) are observed with the contemporaneous coordination of (Glu18, Asp21) or (Glu16, Glu18), and (Glu24, Asp52) or (Glu51, Asp52) donors. The results of this work suggest that the combined application of spectroscopic, spectrometric, and computational techniques allow the complete characterization of the ternary systems formed by a V compound and a model protein such as ubiquitin. The same approach can be applied, eventually changing the spectroscopic/spectrometric techniques, to study the interaction of other metal species with other proteins.

Biospeciation of Potential Vanadium Drugs of Acetylacetonate in the Presence of Proteins

“…to those revealed with V III and recently published, that indicate the formation of the adducts n[V IV O(acac)]-Ub, with n = 1-3 (Ugone et al, 2019). For the system containing Ub as well, EPR measurements indicated the complete transformation of V III (acac) 3 to V IV O(acac) + moiety, which in solution interacts with ubiquitin ( Figure 3B).…”

“…The two solutions are displayed in Figures 5A,B, showing that with increasing the strength of the axial interaction with Ala107 decreases the strength of the contact of V=O with Trp63 and viceversa; in When the interaction of V IV O species and ubiquitin is examined, the data indicated that two main sites exist. The first is based on the coordination of (Glu 16, Glu18; site 1) or (Glu18, Asp21; site 1') (Ugone et al, 2019); the two sites are mutually exclusive and have F mean in the range 39.3-44.3 with population between 14 and 20%. The second site is due to the equatorial binding of the couple (Glu24, Asp52; site 2) or (Glu51, Asp52; site 2') (Ugone et al, 2019); in this case too, these sites are not independent with F mean = 34.9-37.2 and population = 12-88%.…”

“…The first is based on the coordination of (Glu 16, Glu18; site 1) or (Glu18, Asp21; site 1') (Ugone et al, 2019); the two sites are mutually exclusive and have F mean in the range 39.3-44.3 with population between 14 and 20%. The second site is due to the equatorial binding of the couple (Glu24, Asp52; site 2) or (Glu51, Asp52; site 2') (Ugone et al, 2019); in this case too, these sites are not independent with F mean = 34.9-37.2 and population = 12-88%. The two sites are shown in Figure 6 and the values of F max , F mean and population in Table 1.…”

Integrated experimental/computational approaches to characterize the systems formed by vanadium with proteins and enzymes

“…7). The described integrated strategy has been used in a series of works to fully rationalize and characterize the binding sites of V IV O 2+ to other abundant serum proteins, namely, Hb, apo-hTf 143 and holo-hTf, and IgG, as well as to model proteins, such as ubiquitin (Ub) 144 and myoglobin (Mb). 145 We believe that, since V IV O 2+ is the most important active species released by antidiabetic and antitumor VCs, characterization at the molecular level of its binding sites could open new possibilities to understand the mechanism of action of novel V based drugs.…”

Crystal structures of a series of bis(acetylacetonato)oxovanadium(IV) complexes containing N-donor pyridyl ligands

“…Oxovanadium complexes chelated by two acetylacetonate ligands form a five-coordinate bonding system that can act as a Lewis acid (Nenashev et al 2015;Ugone et al, 2019;Costa Pessoa, 2015;Correia et al 2017). This system can undergo a reaction with a Lewis base to increase its coordination ISSN 2056-9890 bonding number to six.…”