Analysis of Structure-Activity Relationships Based on the HCV SLIIb IRES RNA-Targeting GGHYRFK-Cu Complex

摘要

New therapeutics for the targeting of the hepatitis C virus have been released in recent years. Although these therapies are less prone to resistance, they are still administered in cocktails as a combination of drugs targeting various aspects of the viral life cycle. Herein, we aim to contribute to an arsenal of new HCV therapeutics by targeting HCV internal ribosomal entry sequence (IRES) RNA via development of catalytic metallodrugs that function to degrade rather than inhibit the target molecule. Based on a previously characterized HCV IRES stem-loop IIb RNA-targeting metallopeptide Cu-GGHYrFK (1-Cu), an all L-analogue (3-Cu) and a series of additional complexes with single alanine substitutions in the targeting domain were prepared and screened to determine the influence each amino acid side-chain on RNA localization and recognition, and catalytic reactivity toward the RNA. Additional substitutions of the tyrosine position of complex 3-Cu were also investigated. Good agreement of calculated and measured binding affinities provided support for in silico modeling of the SLIIb RNA binding site and correlations with RNA cleavage sites. Examination of cleavage productions from reaction of the Cu-complexes with the SLIIb provided mechanistic insights with the first observation of the 5′-geminal diol and 5′-phosphopropenal as products through use of a Cu-ATCUN catalytic motif. Together, the data yielded insights on structure-function relationships that will guide future optimization efforts.