Recombinant genes expression hosts

Thus, xylA, bgaS, and abfA promoter-based expression vectors were designed and are now commoidy used to drive recombinant gene expression in P. canescens host. 

Gene Expression Systems. One of the potentials of genetic engineering of microbes is production of large amounts of recombinant proteias (12,13). This is not a trivial task. Each proteia is unique and the stabiUty of the proteia varies depending on the host. Thus it is not feasible to have a single omnipotent microbial host for the production of all recombinant proteias. Rather, several microbial hosts have to be studied. Expression vectors have to be tailored to the microbe of choice. 

E. coli strain BL21(DE3) (F ompT ksdSafra ms ) gal dcm) (Novagen, Madison, WI, USA) was used as a host for recombinant OPH expression. Recombinant plasmids pTOH and pEOH that contain OPH gene fused with hexa-histidine affinity tag under trc and T7 promoter, respectively, as control vectors and pTTOH and pETOH that contain OPH gene fused with Tat signal sequence and hexa-histidine affinity tag under trc and T7 promoter, respectively, were used (Fig. 1). 

DNA plasmid-based treatment ( gene therapy ) is considered an alternative to the one based on classical chemical drugs or proteins recovered from recombinant cells. Treatment of acquired and inherent genetic diseases as well as the use of DNA for the purpose of vaccination are potential applications of plasmid DNA (pDNA). The plasmid carries information that allows protein expression in the targeted human cells as well as eukaryotic regulatory elements and specific prokaryotic sequences that control replication in the host cell, see Fig. 10. Formulation is required for ex- or in-vivo administration. Selected systems for gene expression can be viral or non-viral. 

Here, we describe the various alternatives to the use of E. coli expression hosts for heterologous gene expression. Advantages and disadvantages for the different expression systems are discussed, and practical aspects of expression technologies are also described. The feasibility of isotope labeling of recombinantly expressed proteins and their potential use for NMR is also discussed, since the costs and quantities of recombinant proteins produced depend on the system being used. 

Encodes subunit of integration host factor (IHF), involved in site-specific recombination, replication, transposition, regulation of gene expression Required for recombinational repair... 

Expression of genes at a regularly low level, resulting in a low level of product, occurs in every organism. For recombinant proteins, overexpression which leads to considerably enhanced amounts of the recombinant protein is desired. Success of an attempt at recombinant overexpression cannot be predicted as of yet and depends on many factors, such as the protein to be expressed, host, vector, promoter, culture conditions, and, last but not least, the experience of the investigator. 

In some cases, it is preferable that the expression of the target gene occurs in a predetermined phase of the cell cycle or growth and/or in a specific cell type. The recent findings of promoters that fulfill these requirements facilitated synchronizing the expression of recombinant proteins with the cell cycle, and enlarged the list of suitable expression hosts (Blau and Rossi, 1999 Nettelbeck et al., 1999). 

---