Home About us Contact
|
Home About us Contact | ||
|
|
||
Heterologous Gene Expression (heterologous + gene_expression)
Selected AbstractsHeterologous gene expression in Lactococcus lactis; expression of the Azotobacter vinelandii algE6 gene product displaying mannuronan C-5 epimerase activityFEMS MICROBIOLOGY LETTERS, Issue 2 2003Janet M. Blatny Abstract The Azotobacter vinelandii mannuronan C-5 epimerases AlgE1,7 can be used to improve the properties of the commercially important polysaccharide alginate that is widely used in a variety of products, such as food and pharmaceuticals. Since lactic acid bacteria are generally regarded as safe, they are attractive candidates for production of the epimerases. A. vinelandii genes are GC-rich, in contrast to those of lactic acid bacteria, but we show here that significant expression levels of the epimerase AlgE6 can be obtained in Lactococcus lactis using the nisin-controlled expression system. A 1200-fold induction ratio was obtained resulting in an epimerase activity of 23,900 dpm mg,1 h,1, using a tritiated alginate substrate. The epimerase was detected by Western blotting and nuclear magnetic resonance spectroscopy analysis of its reaction product showed that the enzyme displayed catalytic properties similar to those produced in Escherichia coli. [source] Development of a genetic system for hyperthermophilic Archaea: expression of a moderate thermophilic bacterial alcohol dehydrogenase gene in Sulfolobus solfataricusFEMS MICROBIOLOGY LETTERS, Issue 1 2003P Contursi Abstract The Escherichia coli/Sulfolobus solfataricus shuttle vector pEXSs was used as a cloning vehicle for the gene transfer and expression of two bacterial genes in Sulfolobus solfataricus. The alcohol dehydrogenase (adh) from the moderate thermophilic Bacillus stearothermophilus (strain LLDR) and a mutagenised version encoding a less thermostable ADH enzyme were the selected genes. S. solfataricus adh promoter and aspartate aminotransferase terminator were used to drive the heterologous gene expression and to guarantee the correct termination of the transcripts, respectively. The constructed vectors were found to be able to carry these ,passenger' genes without undergoing any rearrangements. The active transcription of bacillar mRNAs was ascertained in vivo by RT-PCR. Transformed S. solfataricus expressed functional exogenous ADHs that showed unaffected kinetic and chemical,physical features. [source] Inactivation of the cytochrome P450 gene CYP82E2 by degenerative mutations was a key event in the evolution of the alkaloid profile of modern tobaccoNEW PHYTOLOGIST, Issue 3 2007Manohar Chakrabarti Summary ,,The alkaloid profile of cultivated tobacco (Nicotiana tabacum) is different from that of its two progenitors, Nicotiana sylvestris and Nicotiana tomentosiformis, in that tobacco accumulates nicotine as the most abundant alkaloid, while its ancestors convert nicotine to nornicotine in the senescing leaf. The nicotine-retaining phenotype of tobacco is thought to have evolved through the inactivation of the conversion loci inherited from its two progenitors. Here, the genetic changes associated with the inactivation of the conversion locus derived from N. sylvestris were investigated. ,,Candidate genes were isolated from a N. sylvestris senescing leaf cDNA library and characterized by heterologous gene expression in yeast, site-directed mutagenesis and quantitative real-time polymerase chain reaction. ,,A cytochrome P450 gene, designated NsylCYP82E2, was isolated from N. sylvestris. Located on the chromosomal fragment defined by the N. sylvestris conversion locus, NsylCYP82E2 confers high nicotine N -demethylase (NND) activity in the senescing leaves of N. sylvestris, but the gene is inactivated by two degenerative mutations in tobacco. ,,Collectively with previously published data, these results show that inactivation of NND genes by degenerative mutations and/or transcriptional suppression played a key role in the evolution of the alkaloid profile of modern tobacco. [source] A new metal-inducible promoter for heterologous gene expression in Cupriavidus metalliduransBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2010Article first published online: 1 JUN 2010 No abstract is available for this article. [source] | ||||||||||