TY - JOUR
T1 - Implications of oxidovanadium(IV) binding to actin
AU - Moura, José João Galhardas de
PY - 2011/1/1
Y1 - 2011/1/1
N2 - Oxidovanadium(IV), a cationic species (VO(2+)) of vanadium(IV), binds to several proteins, including actin. Upon titration with oxidovanadium(IV), approximately 100% quenching of the intrinsic fluorescence of monomeric actin purified from rabbit skeletal muscle (G-actin) was observed, with a V(50) of 131 mu M, whereas for the polymerized form of actin (F-actin) 75% of quenching was obtained and a V(50) value of 320 mu M. Stern-Volmer plots were used to estimate an oxidovanadium(IV)-actin dissociation constant, with K(d) of 8.2 mu M and 64.1 mu M VOSO(4), for G-actin and F-actin, respectively. These studies reveal the presence of a high affinity binding site for oxidovanadium(IV) in actin, producing local conformational changes near the tryptophans most accessible to water in the three-dimensional structure of actin. The actin conformational changes, also confirmed by (1)H NMR, are accompanied by changes in G-actin hydrophobic surface, but not in F-actin. The (1)H NMR spectra of G-actin treated with oxidovanadium(IV) clearly indicates changes in the resonances ascribed to methyl group and aliphatic regions as well as to aromatics and peptide-bond amide region. In parallel, it was verified that oxidovanadium(IV) prevents the G-actin polymerization into F-actin. In the 0-200 mu M range, VOSO(4) inhibits 40% of the extent of polymerization with an IC(50) of 15.1 mu M, whereas 500 mu M VOSO(4) totally suppresses actin polymerization. The data strongly suggest that oxidovanadium(IV) binds to actin at specific binding sites preventing actin polymerization. By affecting actin structure and function, oxidovanadium(IV) might be responsible for many cellular effects described for vanadium.
AB - Oxidovanadium(IV), a cationic species (VO(2+)) of vanadium(IV), binds to several proteins, including actin. Upon titration with oxidovanadium(IV), approximately 100% quenching of the intrinsic fluorescence of monomeric actin purified from rabbit skeletal muscle (G-actin) was observed, with a V(50) of 131 mu M, whereas for the polymerized form of actin (F-actin) 75% of quenching was obtained and a V(50) value of 320 mu M. Stern-Volmer plots were used to estimate an oxidovanadium(IV)-actin dissociation constant, with K(d) of 8.2 mu M and 64.1 mu M VOSO(4), for G-actin and F-actin, respectively. These studies reveal the presence of a high affinity binding site for oxidovanadium(IV) in actin, producing local conformational changes near the tryptophans most accessible to water in the three-dimensional structure of actin. The actin conformational changes, also confirmed by (1)H NMR, are accompanied by changes in G-actin hydrophobic surface, but not in F-actin. The (1)H NMR spectra of G-actin treated with oxidovanadium(IV) clearly indicates changes in the resonances ascribed to methyl group and aliphatic regions as well as to aromatics and peptide-bond amide region. In parallel, it was verified that oxidovanadium(IV) prevents the G-actin polymerization into F-actin. In the 0-200 mu M range, VOSO(4) inhibits 40% of the extent of polymerization with an IC(50) of 15.1 mu M, whereas 500 mu M VOSO(4) totally suppresses actin polymerization. The data strongly suggest that oxidovanadium(IV) binds to actin at specific binding sites preventing actin polymerization. By affecting actin structure and function, oxidovanadium(IV) might be responsible for many cellular effects described for vanadium.
KW - Vanadium
KW - Intrinsic fluorescence
KW - Actin
KW - Oxidovanadium(IV)
KW - Actin polymerization
U2 - 10.1016/j.jinorgbio.2011.02.010
DO - 10.1016/j.jinorgbio.2011.02.010
M3 - Article
C2 - 21497575
SN - 0162-0134
VL - 105
SP - 777
EP - 783
JO - Journal of Inorganic Biochemistry
JF - Journal of Inorganic Biochemistry
IS - 6
ER -