Interactions among SARS-CoV accessory proteins revealed by bimolecular fluorescence complementation assay

The accessory proteins (3a, 3b, 6, 7a, 7b, 8a, 8b, 9b and ORF14), predicted unknown proteins (PUPs) encoded by the genes, are considered to be unique to the severe acute respiratory syndrome coronavirus (SARS-CoV) genome. These proteins play important roles in various biological processes mediated by interactions with their partners. However, very little is known about the interactions among these accessory proteins. Here, a EYFP (enhanced yellow fluorescent protein) bimolecular fluorescence complementation (BiFC) assay was used to detect the interactions among accessory proteins. 33 out of 81 interactions were identified by BiFC, much more than that identified by the yeast two-hybrid (Y2H) system. This is the first report describing direct visualization of interactions among accessory proteins of SARS-CoV. These findings attest to the general applicability of the BiFC system for the verification of protein-protein interactions.

Estudo da participação das proteínas Paxilina e Miosina-va na infectividade do Vírus Linfotrópico de Células T Humanas do tipo 1 (HTLV-1) / Study participation of Paxillin proteins and myosin-va in infectivity of the virus lymphotropic Human T cells type 1 (HTLV-1)

As ORFs I e IV do genoma do HTLV-1 codificam, respectivamente, as proteínas p12/p8 (acessória) e Tax (regulatória). p12/p8, de 99 aminoácidos, pode ser clivada em sua extremidade amino terminal gerando a proteína p8. A primeira clivagem proteolítica de p12 remove o sinal de retenção ao RE, enquanto a segunda clivagem, gera o produto de 8kDa, referido como p8. p12 localiza-se no sistema de endomembranes, residindo em RE e aparato de Golgi, enquanto p8 dirige-se para a membrana plasmática, onde é recrutada para a sinapse imunológica, através da ligação com o receptor de células T (TCR), além de participar da sinapse virológica e da formação de conduítes. A proteína Tax, por outro lado, atua como transativador transcricional do HTLV-1, sendo referida também na indução da expressão de diversos genes celulares, aumentando a proliferação e a migração das células infectadas. Na via de transporte de vesículas secretórias, vesículas produzidas como pós-Golgi são transportadas ao longo do citoesqueleto por motores celulares. A Miosina-Va, um motor não convencional, transporta diversos cargos, incluindo vesículas secretórias, vesículas sinápticas e de retículo endoplasmático. Outra proteína relacionada ao citoesqueleto é a Paxilina, que atua como molécula adaptadora nas adesões focais e cuja expressão está aumentada em indivíduos TSP-HAM...

HTLV-1 ORFs I and IV encode respectively p12/p8 (accessory protein) and Tax (regulatory protein). The 99 amino acid p12 protein can be proteolytically cleaved at the amino terminus to generate the p8 protein. The first proteolytic cleavage removes the ER retention/retrieval signal at the amino terminus of p12, while the second cleavage generates the p8 protein. The p12 protein localizes to cellular endomembranes, within the ER and Golgi apparatus, while p8 traffics to lipid rafts at the cell surface and is recruited to the immunological synapse upon T-cell receptor (TCR) ligation, virological synapse and conduits. Tax on the other hand acts as viral transactivator and induces expression of many cellular genes, increasing proliferation and migration of infected cells. In secretory vesicle transport, vesicles produced as post-Golgi are moved along the cytoskeleton by motor proteins. The unconventional myosin motor, Myosin-Va, moves several cargoes including secretory vesicles, synaptic vesicles, and the endoplasmic reticulum. Another cytoskeleton associated protein is Paxillin, an adapter on focal adhesions which expression is increased in TSP-HAM patients...

Papel de las prtteínas reguladoras y accesorias del vih-1 en la patogénesis de esa infección / Role of the regulatory and accesory proteins of HIV- 1 in its pathogenisis

Desde el descubrimiento del virus de inmunodeficiencia humana tipo 1 (VIH-1) como agente etiológico del síndrome de inmunodeficiencia adquirida (SIDA) se han descrito los procesos más importantes que hacen parte del ciclo replicativo del virus y que a su vez participan de la fisiopatología tan compleja que caracteriza a esta infección. A pesar de los avances realizados en el desarrollo de medicamentos antirretrovirales y de los logros alcanzados en el control de la replicación viral, hechos que se reflejan en un aumento en la expectativa y calidad de vida de los individuos infectados, la terapia actual no permite una reconstitución inmunológica total y está acompañada de efectos tóxicos secundarios y de la aparición de resistencia viral. Esto ha obligado a mantener la búsqueda constante de nuevos blancos terapéuticos que ofrezcan alternativas en la lucha contra esta pandemia. Hasta hace pocos años se creía que las proteínas accesorias y reguladoras del VIH1 no ejercían un papel significativo en el ciclo replicativo del virus y en la patogénesis de la infección; sin embargo, estudios recientes indican que estas proteínas ejercen funciones esenciales en diferentes etapas del proceso replicativo y por ende son responsables de muchos efectos asociados a la patogénesis viral. Por estos hallazgos, las proteínas accesorias y reguladoras del VIH-1 constituyen un blanco promisorio en el desarrollo de nuevos medicamentos que complementen los antirretrovirales disponibles en la actualidad. En esta revisión se describe la función de las proteínas reguladoras y accesorias del VIH-1 en el ciclo replicativo viral y su participación en el proceso patogénico de esta infección.

Since the discovery of HIV-1 as the etiological agent of the acquired immunodeficiency syndrome (AIDS), the main processes involved in its replication cycle and responsible for the complex physiopathology of this infection have been described. Despite the advances in the development of new antiretrovirals and their impact in the quality and life expectancy of infected individuals, the current therapy does not allow a complete immune reconstitution and is also associated with deleterious side effects and the appearance of viral resistance. Therefore the search for new therapeutic targets is required to face this pandemic. The role of the accessory and regulatory proteins of the HIV- 1 in the replication cycle and in the pathogenesis of the infection has been ignored for several years now; however, recent studies indicated that these proteins play essential roles in the replication cycle, being responsible for several processes associated to viral pathogenesis. These findings have underlined the importance of these proteins as promissory targets in the development of new therapeutic agents. In this review, we detailed the role of each one of the HIV-1’s regulatory and accessory proteins in the replicative cycle and in the pathogenesis of this infection.