Vaccinia Virus Proteins A52 and B14 Share a Bcl-2–Like Fold but Have Evolved to Inhibit NF-κB rather than Apoptosis
Figure 5
A52 and B14 lack a surface BH3-peptide binding groove and do not block apoptosis.
(A) HeLa cells were transfected with vectors expressing FLAG-tagged A52, B14, N1, M11, untagged Bcl-xL or empty control vector (pCI; EV) together with CD20 expression vector. After a further 24 h, cells were treated with 0.5 µM staurosporine for 1 h or left untreated and assayed for mitochondrial dysfunction by JC-1 staining and FACS analysis. Data are expressed as means±standard deviation of 3 independent experiments. Statistics: two-tailed Student's t-Test (*P<0.05, **P<0.005). (B and C) The BH3-peptide binding groove of M11 is occluded in both A52 and B14. The structures of (B) A52 (orange ribbon) and (C) B14 (magenta ribbon) are shown superposed upon the structure of myxoma virus M11 (light grey ribbon) in complex with the BH3 peptide of human Bak-2 (lime green helix; PDB ID 2jby). Side chains that block the BH3-peptide binding groove are shown as sticks. (D) Stereogram depicting superposed Cα traces of A52 (orange), B14 (magenta), VACV N1 (cyan; PDB ID 2uxe), myxoma virus M11 (light grey; PDB IDs 2jbx and 2jby), mouse Bcl-xL (yellow; PDB IDs 1pq0 and 1pq1) and Epstein-Barr virus BHRF1 (dark blue; PDB ID 1q59). Two conformations of M11 and Bcl-xL are shown (in the presence and absence of bound BH3 peptide). The BH3 peptide of human Bak-2 in complex with myxoma virus M11 is shown (lime green helix; PDB ID 2jby).