tailieunhanh - Báo cáo y học: "Self-association of the Lentivirus protein, Nef"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài: Self-association of the Lentivirus protein, Nef. | Kwak et al. Retrovirology 2010 7 77 http content 7 1 77 RETR0VIR0L0GY RESEARCH Open Access Self-association of the Lentivirus protein Nef Youn Tae Kwak3 Alexa Raney4 Lillian S Kuo4 Sarah J Denial1 Brenda RS Temple2 J Victor Garcia1 John L Foster1 Abstract Background The HIV-1 pathogenic factor Nef is a multifunctional protein present in the cytosol and on membranes of infected cells. It has been proposed that a spatial and temporal regulation of the conformation of Nef sequentially matches Nef s multiple functions to the process of virion production. Further it has been suggested that dimerization is required for multiple Nef activities. A dimerization interface has been proposed based on intermolecular contacts between Nefs within hexagonal Nef FynSH3 crystals. The proposed dimerization interface consists of the hydrophobic B-helix and flanking salt bridges between R105 and D123. Here we test whether Nef self-association is mediated by this interface and address the overall significance of oligomerization. Results By co-immunoprecipitation assays we demonstrated that HIV-1Nef exists as monomers and oligomers with about half of the Nef protomers oligomerized. Nef oligomers were found to be present in the cytosol and on membranes. Removal of the myristate did not enhance the oligomerization of soluble Nef. Also SIVNef oligomerizes despite lacking a dimerization interface functionally homologous to that proposed for HIV-1Nef. Moreover HIV-1Nef and SIVNef form hetero-oligomers demonstrating the existence of homologous oligomerization interfaces that are distinct from that previously proposed R105-D123 . Intracellular cross-linking by formaldehyde confirmed that SF2Nef dimers are present in intact cells but surprisingly self-association was dependent on R105 but not D123. SIVMAC239Nef can be cross-linked at its only cysteine C55 and SF2Nef is also cross-linked but at C206 instead of C55 suggesting that Nefs exhibit multiple dimeric structures. .