The N terminus of orf virus-encoded protein 002 inhibits acetylation of NF-?B p65 by preventing Ser(276) phosphorylation.

PloS one

PubMedID: 23536830

Ning Z, Zheng Z, Hao W, Duan C, Li W, Wang Y, Li M, Luo S. The N terminus of orf virus-encoded protein 002 inhibits acetylation of NF-?B p65 by preventing Ser(276) phosphorylation. PLoS ONE. 2013;8(3):e58854.
Orf virus-encoded protein 002 (ORFV002) inhibits NF-?B signaling pathway by decreasing the acetylation of NF-?B-p65 through interference of NF-?B p65's association with NF-?B p300. However, the precise mechanism of how ORFV002 interferes with the NF-?B p65/p300 association is still unknown. Due to similarities of the amino acid sequences of ORFV002 and the adenovirus type 12 (Ad12) E1A protein (E1A-12), we hypothesized that the N-terminal 52 amino acids of ORFV002 might play an important role in this inhibition and constructed several in-frame fusions of ORFV002 to an enhanced green fluorescent protein (EGFP) reporter, including C-terminal and N-terminal deletion mutants of ORFV002. When the N-terminus of ORFV002 was absent, the localization of ORFV002 shifted mainly from the nucleus to the cytoplasm, and it's inhibition of NF-?B transactivation was lost. NF-?B p65 Lys(310) acetylation and Ser(276) phosphorylation were detected in co-transfection experiments with NF-?B p65 and ORFV002 or its mutants with, or without, the N-terminal region. The results showed that the N-terminus of ORFV002 plays a crucial role in inhibiting both the acetylation and phosphorylation of NF-?B p65. Further investigation indicated that ORFV002 and its C-terminal deletion mutants interfered with NF-?B p65 (Ser(276)) phosphorylation induced by mitogen- and stress-activated protein kinase-1 (MSK1) and the interaction between NF-?B p65 and MSK1. Since phosphorylated NF-?B p65 recruits transcriptional co-activators such as p300 and CBP, we concluded that the N-terminus of ORFV002 inhibits acetylation of NF-?B p65 by blocking phosphorylation of NF-?B p65 at Ser(276).