RESUMO
Viral protein R (Vpr) is an accessory protein found in various primate lentiviruses, including human immunodeficiency viruses type 1 and 2 (HIV-1 and HIV-2) as well as simian immunodeficiency viruses (SIVs). Vpr modulates many processes during viral lifecycle via interaction with several of cellular targets. Previous studies showed that HIV-1 Vpr strengthened degradation of Mini-chromosome Maintenance Protein10 (MCM10) by manipulating DCAF1-Cul4-E3 ligase in proteasome-dependent pathway. However, whether Vpr from other primate lentiviruses are also associated with MCM10 degradation and the ensuing impact remain unknown. Based on phylogenetic analyses, a panel of primate lentiviruses Vpr/x covering main virus lineages was prepared. Distinct MCM10 degradation profiles were mapped and HIV-1, SIVmus and SIVrcm Vprs induced MCM10 degradation in proteasome-dependent pathway. Colocalization and interaction between MCM10 with these Vprs were also observed. Moreover, MCM10 2-7 interaction region was identified as a determinant region susceptible to degradation. However, MCM10 degradation did not alleviate DNA damage response induced by these Vpr proteins. MCM10 degradation by HIV-1 Vpr proteins was correlated with G2/M arrest, while induction of apoptosis and oligomerization formation of Vpr failed to alter MCM10 proteolysis. The current study demonstrated a distinct interplay pattern between primate lentiviruses Vpr proteins and MCM10.
Assuntos
Produtos do Gene vpr/metabolismo , Lentivirus de Primatas/genética , Proteínas de Manutenção de Minicromossomo/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Pontos de Checagem do Ciclo Celular , Dano ao DNA , Produtos do Gene vpr/genética , Células HEK293 , HIV-1/genética , HIV-1/fisiologia , Células HeLa , Humanos , Lentivirus de Primatas/química , Proteínas de Manutenção de Minicromossomo/genética , Filogenia , Proteólise , Vírus da Imunodeficiência Símia/genética , Vírus da Imunodeficiência Símia/fisiologiaRESUMO
Lentiviruses are widespread in a variety of vertebrates, often associated with chronic disease states. However, until the recent discovery of the prehistoric endogenous lentiviruses in rabbits (RELIK) and lemurs (PSIV), it was thought that lentiviruses had no capacity for germline integration and were only spread horizontally in an exogenous fashion. The existence of RELIK and PSIV refuted these ideas, revealing lentiviruses to be present in a range of mammals, capable of germline integration, and far more ancient than previously thought. Using Gag sequences reconstructed from the remnants of these prehistoric lentiviruses, we have produced chimeric lentiviruses capable of infecting nondividing cells and determined structures of capsid domains from PSIV and RELIK. We show that the structures from these diverse viruses are highly similar, containing features found in modern-day lentiviruses, including a functional cyclophilin-binding loop. Together, these data provide evidence for an ancient capsid-cyclophilin interaction preserved throughout lentiviral evolution.
Assuntos
Proteínas do Capsídeo/química , Ciclofilina A/metabolismo , Retrovirus Endógenos/química , Retrovirus Endógenos/genética , Evolução Molecular , Lentivirus/química , Lentivirus/genética , Animais , Sequência de Bases , Capsídeo/metabolismo , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/metabolismo , Cristalografia por Raios X , Ciclofilina A/química , Metilação de DNA , Retrovirus Endógenos/fisiologia , Produtos do Gene gag/química , Produtos do Gene gag/metabolismo , Genes Virais , Genes gag , Lemur/virologia , Lentivirus/fisiologia , Lentivirus de Primatas/química , Lentivirus de Primatas/genética , Lentivirus de Primatas/fisiologia , Modelos Moleculares , Estrutura Terciária de Proteína , Coelhos , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/metabolismo , Vírion/metabolismoRESUMO
Neutralizing antibody titers have been correlated with protection following vaccination against many viral pathogens. The logical target of protective antibody responses elicited by potential HIV vaccines should be the viral Env spike on the surface of the virion. However, the potency and titers of neutralizing antibodies that arise during HIV infection are generally discouragingly low and the antibodies that do arise recognize mainly autologous virus. This is thought to be a result of a combination of immunodominance of hypervariable regions of the Env protein that can easily escape neutralization, antibody reactivity to gp160 "decoy" protein in cell surface debris or monomeric gp120, conformational constraints within the Env trimer that create unfavorable antibody binding conditions and extensive glycosylation of the exposed regions of Env within the trimer. This review will describe current knowledge regarding glycosylation as a mechanism of neutralization resistance and discuss experimental approaches used to overcome this resistance. Part of the strategy toward development of an optimally immunogenic Env spike will likely require modification of Env glycosylation.
