RESUMO
HDM2 binds to an alpha-helical transactivation domain of p53, inhibiting its tumor suppressive functions. A miniaturized thermal denaturation assay was used to screen chemical libraries, resulting in the discovery of a novel series of benzodiazepinedione antagonists of the HDM2-p53 interaction. The X-ray crystal structure of improved antagonists bound to HDM2 reveals their alpha-helix mimetic properties. These optimized molecules increase the transcription of p53 target genes and decrease proliferation of tumor cells expressing wild-type p53.
Assuntos
Benzodiazepinas/síntese química , Proteínas Nucleares/antagonistas & inibidores , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteína Supressora de Tumor p53/agonistas , Benzodiazepinas/química , Benzodiazepinas/farmacologia , Sítios de Ligação , Linhagem Celular Tumoral , Técnicas de Química Combinatória , Cristalografia por Raios X , Humanos , Modelos Moleculares , Mimetismo Molecular , Estrutura Molecular , Proteínas Proto-Oncogênicas c-mdm2 , Estereoisomerismo , Relação Estrutura-Atividade , Proteína Supressora de Tumor p53/biossínteseRESUMO
The angiotensin-converting enzyme (ACE)-related carboxypeptidase, ACE2, is a type I integral membrane protein of 805 amino acids that contains one HEXXH + E zinc-binding consensus sequence. ACE2 has been implicated in the regulation of heart function and also as a functional receptor for the coronavirus that causes the severe acute respiratory syndrome (SARS). To gain further insights into this enzyme, the first crystal structures of the native and inhibitor-bound forms of the ACE2 extracellular domains were solved to 2.2- and 3.0-A resolution, respectively. Comparison of these structures revealed a large inhibitor-dependent hinge-bending movement of one catalytic subdomain relative to the other ( approximately 16 degrees ) that brings important residues into position for catalysis. The potent inhibitor MLN-4760 ((S,S)-2-[1-carboxy-2-[3-(3,5-dichlorobenzyl)-3H-imidazol4-yl]-ethylamino]-4-methylpentanoic acid) makes key binding interactions within the active site and offers insights regarding the action of residues involved in catalysis and substrate specificity. A few active site residue substitutions in ACE2 relative to ACE appear to eliminate the S(2)' substrate-binding subsite and account for the observed reactivity change from the peptidyl dipeptidase activity of ACE to the carboxypeptidase activity of ACE2.