Potent Antiviral HIV-1 Protease Inhibitor GRL-02031 Adapts to the Structures of Drug Resistant Mutants with Its P1′-Pyrrolidinone Ring

GRL-02031 (1) is an HIV-1 protease (PR) inhibitor containing a novel P1' (R)-aminomethyl-2-pyrrolidinone group. Crystal structures at resolutions of 1.25-1.55 angstrom were analyzed for complexes of 1 with the PR containing major drug resistant mutations, PRI47V, PRL76V, PRV82A, and PRN88D. Mutations of I47V and V82A alter residues in the inhibitor-binding site, while L76V and N88D are distal mutations having no direct contact with the inhibitor. Substitution of a smaller amino acid in PRI47V and PRL76V and the altered charge of PRN88D are associated with significant local structural changes compared to the wild-type PR, while substitution of alanine in PRV82A, increases the size of the S1' subsite. The P1' pyrrolidinone group of 1 accommodates to these local changes by assuming two different conformations. Overall, the conformation and interactions of 1 with PR mutants resemble those of PRWT with similar inhibition constants in good agreement with the antiviral potency on multidrug resistant HIV-1.