Chimeric clones

Chapter 13 Recombinant DNA Cloning and Creation of Chimeric Genes... 

Manipulation of the DNA to change its structure, so-called genetic engineering, is a key element in cloning (eg, the construction of chimeric molecules) and can... 

Figure 3.4 Improvement of the activity of chimeric NRPSs using directed evolution. (1) A heterologous A domain is swapped into an NRPS, typically resulting in a significant loss of synthetase activity. (2) A library of chimeric synthetase mutants is constructed in which the heterologous A domain has been diversified (for example, by error-prone PCR). (3) The library is subjected to an in vivo screen for production of the unnatural nonribosomal peptide derivative. (4) Clones showing improved production are characterized and subjected to further rounds of diversification and screening...

Another methodological artifact are chimeric sequences which can be formed during PCR amphfication of mixed template at a frequency of several percent. The assumption that each rRNA sequence is equivalent to a species is as shaky as the still wide spread assumption that from the frequency of an rRNA clone in a library the relative abundance of the respective organism in the environment can be estimated. 

By early 1990 Genentech had reported the development of murine monoclonal antibodies with therapeutic potential against tumor cells that overexpress erbB-2. One of these clones was humanized to produce a mouse/human chimeric form termed 4D5 and determined to be a suitable candidate for preclinical and clinical studies [23]. In 1998 the FDA approved the humanized monoclonal antibody, now... 

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