Replication of a chimeric origin containing elements from Epstein-Barr virus ori P and bovine papillomavirus minimal origin

Recombinant protein production by transient gene transfer into Mammalian cells

The timely availability of recombinant proteins in sufficient quantity and of validated quality is of utmost importance in driving drug discovery and the development of low molecular weight compounds, as well as for biotherapeutics. Transient gene expression (TGE) in mammalian cells has emerged as a promising technology for protein generation over the past decade as TGE meets all the prerequisites with respect to quantity and quality of the product as well as cost-effectiveness and speed of the process. Optimized protocols have been developed for both HEK293 and CHO cell lines which allow protein production at any desired scale up to >100 l and in milligram to gram quantities. Along with an overview on current scientific and technological knowledge, detailed protocols for expression of recombinant proteins on small, medium, and large scale are discussed in the following chapter.

Analysis of chromatin attachment and partitioning functions of bovine papillomavirus type 1 E2 protein

Recent studies have suggested that the tethering of viral genomes to host cell chromosomes could provide one of the ways to achieve their nuclear retention and partitioning during extrachromosomal maintenance in dividing cells. The data we present here provide firm evidence that the partitioning of the bovine papillomavirus type 1 (BPV1) genome is dependent on the chromatin attachment process mediated by viral E2 protein and its multiple binding sites. On the other hand, the attachment of E2 and the E2-mediated tethering of reporter plasmids to host chromosomes are not necessarily sufficient for efficient partitioning, suggesting that additional E2-dependent activities might be involved in the latter process. The activity of E2 protein in chromatin attachment and partitioning is more sensitive to the point mutations in the N-terminal domain than its transactivation and replication initiation functions. Therefore, at least part of the interactions of the E2 N-terminal domain with its targets during the chromatin attachment and partitioning processes are likely to involve specific receptors not involved in transactivation and replication activities of the protein. The mutational analysis also indicates that the binding of E2 to chromatin is not achieved through interaction of linear N-terminal subsequences of the E2 protein with putative receptors. Instead, the composite surface elements of the N-terminal domain build up the receptor-binding surface of E2. In this regard, the interaction of BPV1 E2 with its chromosomal targets clearly differs from the interactions of LANA1 protein from Kaposi's sarcoma-associated human herpesvirus and EBNA1 from Epstein-Barr virus with their specific receptors.