RESUMO
Bacterial persistence is the ability of individual cells to randomly enter a period of dormancy during which the cells are protected against antibiotics. In Escherichia coli, persistence is regulated by the activity of a protein kinase HipA and its DNA-binding partner HipB, which is a strong inhibitor of both HipA activity and hip operon transcription. The crystal structure of the HipBA complex was solved by application of the SAD technique to a mercury derivative. In this article, the fortuitous and interesting effect of mercury soaks on the native HipBA crystals is discussed as well as the intriguing tryptophan-binding pocket found on the HipA surface. A HipA-regulation model is also proposed that is consistent with the available structural and biochemical data.
Assuntos
Proteínas de Ligação a DNA/química , Proteínas de Escherichia coli/química , Escherichia coli/enzimologia , Inibidores de Proteínas Quinases/química , Antibacterianos/uso terapêutico , Sítios de Ligação , Cristalização , Cristalografia por Raios X , Proteínas de Ligação a DNA/metabolismo , Farmacorresistência Bacteriana , Infecções por Escherichia coli/tratamento farmacológico , Infecções por Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/metabolismo , Regulação Bacteriana da Expressão Gênica , Genes de Troca/genética , Humanos , Mercúrio/metabolismo , Óperon , Conformação Proteica , Inibidores de Proteínas Quinases/metabolismo , Relação Estrutura-Atividade , Triptofano/metabolismoRESUMO
Nicotinamide adenine dinucleotide synthetase (NadE) is an essential enzyme for bacterial pathogens and is thus a promising antibacterial target. It catalyzes the conversion of nicotinic acid adenine dinucleotide to nicotinamide adenine dinucleotide. Changes in chemical shifts that occur in the nicotinic acid ring as it is converted to nicotinamide can be used for monitoring the reaction. A robust nuclear magnetic resonance-based activity assay was developed using robotically controlled reaction initiation and quenching. The single-enzyme assay has less potential for false positives compared to a coupled activity assay and is especially well suited to the high concentration of compounds in fragment screens. The assay has been used to screen fragment libraries for NadE inhibitors.
Assuntos
Amida Sintases/química , Amida Sintases/fisiologia , Espectroscopia de Ressonância Magnética , Amida Sintases/genética , Sequência de Aminoácidos , Dados de Sequência Molecular , Niacina/química , Niacina/metabolismo , Niacinamida/biossíntese , Niacinamida/química , Staphylococcus aureus/enzimologia , Staphylococcus aureus/genéticaRESUMO
Nicotinamide (2) is a potent and selective inhibitor of the PDE4D isozyme and as a chemical tool selectively blocks eosinophil mediator release and chemotaxis thus linking the role of PDE4D to eosinophil function.
Assuntos
3',5'-AMP Cíclico Fosfodiesterases/fisiologia , Eosinófilos/fisiologia , Leucócitos/fisiologia , Niacinamida/antagonistas & inibidores , Inibidores de Fosfodiesterase/farmacologia , 3',5'-AMP Cíclico Fosfodiesterases/antagonistas & inibidores , Quimiotaxia/efeitos dos fármacos , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4 , Eosinófilos/efeitos dos fármacos , Isoenzimas/antagonistas & inibidores , Isoenzimas/química , Isoenzimas/metabolismo , Leucócitos/efeitos dos fármacos , Inibidores de Fosfodiesterase/química , Rolipram/química , Rolipram/farmacologiaRESUMO
Because of its requirement for signaling by multiple cytokines, Janus kinase 3 (JAK3) is an excellent target for clinical immunosuppression. We report the development of a specific, orally active inhibitor of JAK3, CP-690,550, that significantly prolonged survival in a murine model of heart transplantation and in cynomolgus monkeys receiving kidney transplants. CP-690,550 treatment was not associated with hypertension, hyperlipidemia, or lymphoproliferative disease. On the basis of these preclinical results, we believe JAK3 blockade by CP-690,550 has potential for therapeutically desirable immunosuppression in human organ transplantation and in other clinical settings.