Selective Targeting of the Zinc Finger Domain of HIV Nucleocapsid Protein NCp7 with Ruthenium Complexes

Abstract

Nucleocapsid protein 7 (NCp7) is an attractive target for anti‐HIV drug development. Here we found that ruthenium complexes are reactive to NCp7 and various Ru‐agents exhibit significantly different reactivity. Interestingly, the zinc‐finger domains of NCp7 also demonstrate different affinity to Ru‐complexes; the C‐terminal domain is much more reactive than the N‐terminal domain. Each zinc‐finger domain of NCp7 binds up to three Ru‐motifs, and the ruthenium binding causes zinc‐ejection from NCp7 and disrupts the protein folding. Therefore, ruthenium complexes interfere with the DNA binding of NCp7 and interrupt the protein function. The different reactivity of Ru‐agents suggests a feasible strategy for improving the targeting of NCp7 by ligand design. This work provides an insight into the mechanism of ruthenium complex with NCp7, and suggests more potential application of ruthenium drugs.

Covalent versus Noncovalent Binding of Ruthenium η6‐p‐Cymene Complexes to Zinc‐Finger Protein NCp7

“…The reaction of the five ruthenium complexes with NCp7 were investigated by fluorescence spectroscopy given that Ru‐binding quenches the intrinsic fluorescence of NCp7 (excitation at 280 nm) . The reactions were conducted with NCp7 and different ratios of Ru‐agents (Figure A and S1).…”

“…According to previous reports, the CD spectrum of free NCp7 exhibits a positive ellipticity at ca. 215 nm (Figure S3), which reflects its folded secondary structure . The signal clearly decreased after incubation of NCp7 with Ru‐1 or Ru‐5 , indicating a large perturbation of the structure of NCp7 by the two complexes.…”

“…A member of the S ‐acyl‐2‐mercaptobenzamide thioester family (SAMTs), which is a small molecular NCp7 inhibitor, is undergoing Phase II clinical trials . Metallo‐agents, such as Pt‐, Au‐, and Ru‐complexes, have demonstrated high potential to target zinc‐finger proteins; nevertheless, reactivity and selectivity are crucial for inhibitors in drug development. For instance, arsenic trioxide preferentially binds to the ring‐finger domain of PML over other zinc‐finger proteins, which enables its therapeutic effect for curing acute promyelocytic leukemia .…”

“…HIV Nucleocapsid protein 7 (NCp7) is an emerging target for the development of anti‐HIV drugs . Our previous studies have found that various ruthenium arene complexes exhibit different reactivity to NCp7, and the ligands of Ru‐compounds can greatly influence the reactivity with the protein . Hence, it is interesting to understand how ruthenium complexes bind to the protein and how the binding modes influence the reactivity of Ru‐agents.…”

A dual functional ruthenium arene complex induces differentiation and apoptosis of acute promyelocytic leukemia cells

“…This observation is consistent with a recent report that Ru-binding leads to the uorescence quenching of zinc-nger proteins. 18 It has been reported that the binding of many metallodrugs, such as arsenic, platinum, and ruthenium agents, to zinc-nger proteins induces the release of zinc ions from the proteins. [18][19][20] Here we observed that the reaction of Ru-1 also resulted in zinc release from PML (Fig.…”