The membrane binding and deformation property of vaccinia virus K1 ankyrin repeat domain protein

Membrane lipids are essential participants in cellular events, but only a small number of lipid‐interacting proteins have been characterized. Taking advantage of the small genome (~270 genes) of the vaccinia virus, we screened for soluble lipid‐binding proteins and found 27 proteins to be soluble after expression in Escherichia coli. Among them, 4 proteins were found to strongly bind to the total bovine brain lipid extract (Folch I fraction) that contained large amounts of phosphatidylserine in vitro. Out of the 4 proteins, 3 were unique proteins to viruses. Another protein, K1, solely contained an ankyrin repeat domain (ARD). ARD is conserved in large numbers of proteins in bacteria, archaea, eukaryotes and viruses, suggesting the possibilities of the membrane binding of ARDs in varieties of proteins. Furthermore, K1 deformed the lipid membrane dependently on the charged lipids. The tubulation and membrane binding was enhanced with increased negative membrane charge from phosphatidylinositol 4,5‐bisphosphate (PI(4,5)P₂). The basic amino acid residues in the ARD were essential for membrane deformation, suggesting electrostatic interactions between K1 and the membrane for membrane deformation.     

Deletion of Epstein-Barr virus latent membrane protein 1 gene in united states and Brazilian Hodgkin's disease and reactive lymphoid tissue: High frequency of a 30-bp deletion

A 30-basepair (bp) deletion in the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) gene has been reported in nasopharyngeal carcinoma and EBV-associated malignant lymphomas. Prior studies have found the deletion in about 10% to 28% of cases of Hodgkin's disease (HD), particularly in cases with aggressive histology. We studied the prevalence of 30-bp LMP1 gene deletion in EBV-positive HD in the United States (US) (12 cases) and Brazil (26 cases) with comparison to reactive lymphoid tissues (21 cases) and HD without EBV-positive Reed-Sternberg cells (15 cases). We studied the status of the LMP1 gene by Southern blot hybridization of polymerase chain reaction (PCR) products obtained after amplification with primers spanning the site of the deletion. We also performed EBV typing, EBER1 in situ hybridization, and LMP1 protein immunohistochemistry. EBV was detected in (46%) cases of HD from the US and (96%) cases of Brazilian HD. The 30-bp LMP1 gene deletion was observed in (33%) cases of EBV-positive HD from US, and (46%) cases of Brazilian EBV-positive HD, including 3 cases of type B EBV, as compared with (57%) reactive lymphoid tissues and (60%) cases of EBV-negative HD. US and Brazilian HD showed a higher prevalence of the 30-bp LMP1 gene deletion, compared with studies of others. The unexpected finding of high incidence of 30-bp deletion in LMP1 gene in reactive lymphoid tissue and HD without EBV-positive Reed-Sternberg cells suggests that this deletion may not be relevant to HD pathogenesis in most cases.