Biosynthesis trafficking

DORMANN, P., BALBO, I., BENNING, C., Arabidopsis galactolipid biosynthesis and lipid trafficking mediated by DGD1, Science, 1999, 284,2181-2184. 

The study of individual NRPS domain structures provides important information regarding the specificity and enzymology of individual steps in NRP biosynthesis. However, structural analysis of larger NRPS constructs is necessary to gain insight into aspects related to domain/domain interactions and the overall structure of the synthetase machinery. This information is particularly important for understanding the details of substrate trafficking and will assist efforts toward the rational manipulation of NRPSs. 

Many of the chaperones double as heat shock-proteins (Hsp). When a cell is put under stress that can cause proteins to denature, such as too high a temperature, it produces heat-shock proteins. Their names are abbreviated to Hsp plus their subunit molecular mass in kDa. Hsp70, for example, is a ubiquitous heat-shock protein in eukaryotes. It is known in E. coli as DnaK for historical reasons because it was first discovered from a supposed role in DNA replication. Hsp70 is also important in protein trafficking and the conveying of proteins across membranes, because the denatured state is important in these processes. In protein biosynthesis, the unfolded state of the nascent polypeptide chain is passed on to DnaK, which maintains it in an extended form. The chain, under the influence of ATP and co-chaperones such as DnaJ and GrpE, is handed over to GroEL. 

Ilegems E, Pick HM, Deluz C, Kellenberger S, Vogel H. Noninvasive imaging of 5-HT3 receptor trafficking in live cells from biosynthesis to endocytosis. J Biol Chem 2004 279 53,346-53,352. 

Figure 7.9 Intercellular and subcellular trafficking in alkaloid biosynthesis. A. Tropane alkaloid biosynthesis in Hyoscyamus muticus. B. Terpenoid indole alkaloid biosynthesis in Catharanthus roseus. C. Trafficking of the berberine bridge enzyme in Papaver somniferum cell cultures.

Various glycosidases are involved in the modification, biosynthetic processing and trafficking of glycoproteins. Gastanospermin and swainsonine, plant inhibitors of such glycosidases, interfere with glycoprotein biosynthesis and are consequently very toxic (Table 13.1). 

Carman, G.M., and Henry, S.A., 1999, Phospholipid biosynthesis in the yeast Saccharomyces cerevisiae and interrelationship with other metabolic processes. Prog. Lipid Res. 38 361-399. Chang, H.J., 2001, Role of the unfolded protein response pathway in phospholipid biosynthesis and membrane trafficking in Saccharomyces cerevisiae. Department of Biological Sciences, Carnegie Mellon University. 

Facchini, P.J. and St. Pierre, B. (2005) Synthesis and trafficking of alkaloid biosynthesis enzymes. Curr. Opin. Plant Biol, 8, 657-66. 

Ziegler, J. and Facchini, P.J. (2008) Alkaloid biosynthesis metabolism and trafficking. Annu. Rev. Plant Biol, 59, 735-69. 

Fukuda M. Lysosomal membrane glycoproteins. Structure, biosynthesis, and intracellular trafficking. J. Biol. Chem. 1991 266 21327-21330. 

Figure 5 Proteomics reveals functional secretory vesicle protein systems for neuropeptide biosynthesis, storage, and secretion. Chromaffin secretory vesicles (also known as chromaffin granules) were isolated and subjected to proteomic analyses of proteins in the soluble and membrane components of the vesicles. Protein systems in secretory vesicle function consisted of those for 1) production of hormones, neurotransmitters, and neuromodulatory factors, 2) generating selected internal vesicular conditions for reducing condition, acidic pH conditions maintained by ATPases, and chaperones for protein folding, and 3) vesicular trafficking mechanisms to allow the mobilization of secretory vesicles for exocytosis, which uses proteins for nucleotide-binding, calcium regulation, and vesicle exocytosis. These protein systems are coordinated to allow the secretory vesicle to synthesize and release neuropeptides for cell-cell communication in the control of neuroendocrine functions.

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