Heterogeneity of CK2 phosphorylation sites in the NS5A protein of different hepatitis C virus genotypes.
OBJECTIVE
The hepatitis C virus NS5A protein is phosphorylated by several cellular kinases, including casein kinase 2 (CK2). Little is known about CK2 phosphorylation of NS5A from different HCV genotypes and clinical isolates.


METHODS
NS5A from patients with HCV-1a (24 cases), HCV-1b (9) or HCV-3 (16) was analyzed by direct sequencing and CK2 phosphorylation sites were defined using a well-validated prediction rule. In vitro phosphorylation assays were performed using recombinant CK2 and synthetic peptides or full-length NS5A. In vivo phosphorylation by endogenous CK2 of NS5A expressed in hepatoma cells was also investigated.


RESULTS
The mean number of CK2 sites within full-length NS5A, was significantly higher in HCV-3 compared to HCV-1a (P<0.01) and HCV-1b (P<0.01). The number of CK2 sites was more homogeneous in HCV-3 variants compared to HCV-1a and HCV-1b variants (P<0.05). The number of predicted CK2 sites correlated with the degree of in vitro and in vivo phosphorylation of NS5A by CK2.


CONCLUSIONS
CK2-dependent phosphorylation of NS5A is heterogeneous among different HCV genotypes and clinical isolates. This might have an influence on virus biology and pathogenicity.
Dal Pero
Francesca
F
Venetian Institute of Molecular Medicine (VIMM), University of Padova, Via Orus, 2, Padova 35129, Italy. francesca.dalpero@unipd.it
Di Maira
Giovanni
G
Marin
Oriano
O
Bortoletto
Gladis
G
Pinna
Lorenzo A
LA
Alberti
Alfredo
A
Ruzzene
Maria
M
Gerotto
Martina
M
D001665:Binding Sites; D047390:Casein Kinase II / Q000378:metabolism*; D005838:Genotype; D016174:Hepacivirus / Q000737:chemistry* / Q000235:genetics*; D006801:Humans; D010766:Phosphorylation; D012367:RNA, Viral / Q000235:genetics / Q000302:isolation & purification; D017423:Sequence Analysis, RNA; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000378:metabolism*; D012324:RNA-Dependent RNA Polymerase
D047390:Casein Kinase II; D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase