NF-κB activation is a turn on for vaccinia virus phosphoprotein A49 to turn off NF-κB activation.
Proc Natl Acad Sci U S A
; 116(12): 5699-5704, 2019 03 19.
Article
em En
| MEDLINE
| ID: mdl-30819886
ABSTRACT
Vaccinia virus protein A49 inhibits NF-κB activation by molecular mimicry and has a motif near the N terminus that is conserved in IκBα, ß-catenin, HIV Vpu, and some other proteins. This motif contains two serines, and for IκBα and ß-catenin, phosphorylation of these serines enables recognition by the E3 ubiquitin ligase ß-TrCP. Binding of IκBα and ß-catenin by ß-TrCP causes their ubiquitylation and thereafter proteasome-mediated degradation. In contrast, HIV Vpu and VACV A49 are not degraded. This paper shows that A49 is phosphorylated at serine 7 but not serine 12 and that this is necessary and sufficient for binding ß-TrCP and antagonism of NF-κB. Phosphorylation of A49 S7 occurs when NF-κB signaling is activated by addition of IL-1ß or overexpression of TRAF6 or IKKß, the kinase needed for IκBα phosphorylation. Thus, A49 shows beautiful biological regulation, for it becomes an NF-κB antagonist upon activation of NF-κB signaling. The virulence of viruses expressing mutant A49 proteins or lacking A49 (vΔA49) was tested. vΔA49 was attenuated compared with WT, but viruses expressing A49 that cannot bind ß-TrCP or bind ß-TrCP constitutively had intermediate virulence. So A49 promotes virulence by inhibiting NF-κB activation and by another mechanism independent of S7 phosphorylation and NF-κB antagonism. Last, a virus lacking A49 was more immunogenic than the WT virus.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fosfoproteínas
/
Vaccinia virus
/
NF-kappa B
Limite:
Humans
Idioma:
En
Revista:
Proc Natl Acad Sci U S A
Ano de publicação:
2019
Tipo de documento:
Article