The Mengovirus Leader Protein Suppresses Alpha/Beta Interferon Production by Inhibition of the Iron/Ferritin-Mediated Activation of NF-κB

• DOI: 10.1128/jvi.76.19.9664-9672.2002
• Publication Date: 2002-09-03T23:18:19Z
• Authors: Jan Zoll; Willem J. G. Melc...; Jochem M. D. Galama; Frank J. M. van K...
• Keywords: 0301 basic medicine; Iron; Nitric Oxide Synthase Type II; Pathogenese, epidemiologie en behandeling van microbiële infecties; Protein Serine-Threonine Kinases; Protein Sorting Signals; Pathogenesis, epidemiology, and treatment of microbial infections; Mice; Viral Proteins; 03 medical and health sciences; Animals; Humans; Phosphorylation; Casein Kinase II; Mengovirus; NF-kappa B; Interferon-alpha; Interferon-beta; Protein-Serine-Threonine Kinases; 3. Good health; Apoferritins; Ferritins; Nitric Oxide Synthase; Reactive Oxygen Species; HeLa Cells

ABSTRACTIn our studies on the biological function of the mengovirus leader protein, we identified a casein kinase II (CK-2) phosphorylation site in the protein. Here we report that the mengovirus leader protein can be phosphorylated by CK-2 in vitro. Expression of a recombinant leader protein in which the consensus CK-2 sequence around threonine 47 was disturbed resulted in a mutant protein that could no longer be phosphorylated. The CK-2 consensus sequence was modified by site-directed mutagenesis and subsequently introduced into a mengovirus cDNA clone to investigate the effect of the phosphorylation of the leader protein on virus replication and on the host cell response. Modifications by which the CK-2 consensus sequence was disturbed resulted in mutant viruses with reduced growth kinetics. We demonstrated that the integrity of the CK-2 phosphorylation site of the mengovirus leader protein was specifically related to the suppression of NF-κB activation and subsequent suppression of alpha/beta interferon production in infected cells. We also found that the integrity of the CK-2 phosphorylation site of the leader protein coincided with an increase of ferritin expression in the infected cell. These data indicate that the leader protein suppresses the iron-mediated activation of NF-κB and thereby inhibits alpha/beta interferon expression in the infected cell.