IGEM:MIT/2005/Insulin Producing Bacteria

Hey you guys, I found these papers that may or may not help what we're doing. Take a look.


 * 1) Comparison of the periplasmic receptors for L-arabinose, D-glucose/D-galactose, and D-ribose. Structural and Functional Similarity
 * 2) Conformational stability and domain coupling in D-glucose/D-galactose-binding protein from Escherichia coli
 * 3) Direct detection of glucose by surface plasmon resonance with bacterial glucose/galactose-binding protein
 * 4) Cloning of mglB, the structural gene for the galactose-binding protein of Salmonella typhimurium and Escherichia coli
 * 5) Designed potent multivalent chemoattractants for Escherichia coli
 * 6) A piezoelectric quartz crystal biosensor: the use of two single cysteine mutants of the periplasmic Escherichia coli glucose/galactose receptor as target proteins for the detection of glucose
 * 7) Glucose sensor for low-cost lifetime-based sensing using a genetically engineered protein
 * 8) Properties of the galactose binding protein of Salmonella typhimurium and Escherichia coli
 * 9) Ribose and glucose-galactose receptors. Competitors in bacterial chemotaxis

-In islet B cell, rise in glucose  secret insulin  insulin increases glucose uptake & metabolism. -Insulin is peptide hormone, contains 2 polypeptide chains linked by disulfide, synthesized by B cells. -Biosynthesis of Insulin Insulin is synthesized in significant quantities only in B cells in the pancreas. The insulin mRNA is translated as a single chain precursor called preproinsulin, and removal of its signal peptide during insertion into the endoplasmic reticulum generates proinsulin. Proinsulin consists of three domains: an amino-terminal B chain, a carboxy-terminal A chain and a connecting peptide in the middle known as the C peptide. Within the endoplasmic reticulum, proinsulin is exposed to several specific endopeptidases which excise the C peptide, thereby generating the mature form of insulin. Insulin and free C peptide are packaged in the Golgi into secretory granules which accumulate in the cytoplasm. When the B cell is appropriately stimulated, insulin is secreted from the cell by exocytosis and diffuses into islet capillary blood. C peptide is also secreted into blood, but has no known biological activity. -Bacteria: More on Morphology A more or less typical bacterium, shown here, is comparatively much simpler than a typical eukaryotic cell. View the transmission electron micrograph of a typical bacterium, E. coli, below and compare it with the diagram above.

Bacteria lack the membrane-bound nuclei of eukaryotes; their DNA forms a tangle known as a nucleoid, but there is no membrane around the nucleoid, and the DNA is not bound to proteins as it is in eukaryotes. Whereas eukaryote DNA is organized into linear pieces, the chromosomes, bacterial DNA forms loops. Bacteria contain plasmids, or small loops of DNA, that can be transmitted from one cell to another, either in the course of sex (yes, bacteria have sex) or by viruses. This ability to trade genes with all comers makes bacteria amazingly adaptible; beneficial genes, like those for antibiotic resistance, may be spread very rapidly through bacterial populations. It also makes bacteria favorites of molecular biologists and genetic engineers; new genes can be inserted into bacteria with ease. Bacteria do not contain membrane-bound organelles such as mitochondria or chloroplasts, as eukaryotes do. However, photosynthetic bacteria, such as cyanobacteria, may be filled with tightly packed folds of their outer membrane. The effect of these membranes is to increase the potential surface area on which photosynthesis can take place. The cell membrane is surrounded by a cell wall in all bacteria except one group, the Mollicutes, which includes pathogens such as the mycoplasmas. The composition of the cell wall varies among species and is an important character for identifying and classifying bacteria. In this diagram, the bacterium has a fairly thick cell wall made of peptidoglycan (carbohydrate polymers cross-linked by proteins); such bacteria retain a purple color when stained with a dye known as crystal violet, and are known as Gram-positive (after the Danish bacteriologist who developed this staining procedure). Other bacteria have double cell walls, with a thin inner wall of peptidoglycan and an outer wall of carbohydrates, proteins, and lipids. Such bacteria do not stain purple with crystal violet and are known as Gram-negative.