- Results as:
- Print view
- Endnote (RIS)
- BibTeX
- Table: CSV | HTML
Publications
Publications
Publications
Publications
Research Mission and Profile
Molecular Signal Processing
Bioorganic Chemistry
Biochemistry of Plant Interactions
Cell and Metabolic Biology
Independent Junior Research Groups
Program Center MetaCom
Publications
Good Scientific Practice
Research Funding
Networks and Collaborative Projects
Symposia and Colloquia
Alumni Research Groups
Publications
0
Publications
A cDNA encoding a UDP-glucose:sinapate glucosyltransferase (SGT) that catalyzes the formation of 1-O-sinapoylglucose, was isolated from cDNA libraries constructed from immature seeds and young seedlings of rape (Brassica napus L.). The open reading frame encoded a protein of 497 amino acids with a calculated molecular mass of 55,970 Da and an isoelectric point of 6.36. The enzyme, functionally expressed in Escherichia coli, exhibited broad substrate specificity, glucosylating sinapate, cinnamate, ferulate, 4-coumarate and caffeate. Indole-3-acetate, 4-hydroxybenzoate and salicylate were not conjugated. The amino acid sequence of the SGT exhibited a distinct sequence identity to putative indole-3-acetate glucosyltransferases from Arabidopsis thaliana and a limonoid glucosyltransferase from Citrus unshiu, indicating that SGT belongs to a distinct subgroup of glucosyltransferases that catalyze the formation of 1-O-acylglucosides (β-acetal esters).
Publications
A mutant of Synechocystis sp. strain PCC6803 was obtained by random cartridge mutagenesis, which could not grow at low sodium concentrations. Genetic analyses revealed that partial deletion of the sll 0273 gene, encoding a putative Na+ /H+ exchanger, was responsible for this defect. Physiological characterization indicated that the sll 0273 mutant exhibited an increased sensitivity towards K+ , even at low concentrations, which was compensated for by enhanced concentrations of Na+ . This enhanced Na+ demand could also be met by Li+ . Furthermore, addition of monensin, an ionophore mediating electroneutral Na+ /H+ exchange, supported growth of the mutant at unfavourable Na+ /K+ ratios. Measurement of internal Na+ and K+ contents of wild‐type and mutant cells revealed a decreased Na+ /K+ ratio in mutant cells pre‐incubated at a low external Na+ /K+ ratio, while it remained at the level of the wild type after pre‐incubation at a high external Na+ /K+ ratio. We conclude that the Sll0273 protein is required for Na+ influx, especially at low external Na+ concentrations or low Na+ /K+ ratios. This system may be part of a sodium cycle and may permit re‐entry of Na+ into the cells, if nutrient/Na+ symporters are not functional or operating.
Publications
In the recent past, through advances in development of genetic tools, the budding yeast Kluyveromyces lactis has become a model system for studies on molecular physiology of so-called “Nonconventional Yeasts.” The regulation of primary carbon metabolism in K. lactis differs markedly from Saccharomyces cerevisiae and reflects the dominance of respiration over fermentation typical for the majority of yeasts. The absence of aerobic ethanol formation in this class of yeasts represents a major advantage for the “cell factory” concept and large-scale production of heterologous proteins in K. lactis cells is being applied successfully. First insight into the molecular basis for the different regulatory strategies is beginning to emerge from comparative studies on S. cerevisiae and K. lactis. The absence of glucose repression of respiration, a high capacity of respiratory enzymes and a tight regulation of glucose uptake in K. lactis are key factors determining physiological differences to S. cerevisiae. A striking discrepancy exists between the conservation of regulatory factors and the lack of evidence for their functional significance in K. lactis. On the other hand, structurally conserved factors were identified in K. lactis in a new regulatory context. It seems that different physiological responses result from modified interactions of similar molecular modules.