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A vacuole is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution, though in certain cases they may contain solids which have been engulfed. Vacuoles are formed by the fusion of multiple membrane vesicles and are effectively just larger forms of these. The organelle has no basic shape or size; its structure varies according to the requirements of the cell.
In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form naturally during the processes of secretion (exocytosis), uptake (endocytosis) and transport of materials within the plasma membrane. Alternatively, they may be prepared artificially, in which case they are called liposomes. If there is only one phospholipid bilayer, they are called unilamellar liposome vesicles; otherwise they are called multilamellar. The membrane enclosing the vesicle is also a lamellar phase, similar to that of the plasma membrane, and intracellular vesicles can fuse with the plasma membrane to release their contents outside the cell. Vesicles can also fuse with other organelles within the cell. A vesicle released from the cell is known as an extracellular vesicle.
In a chain-like biological molecule, such as a protein or nucleic acid, a structural motif is a common three-dimensional structure that appears in a variety of different, evolutionary unrelated molecules. Motifs do not allow us to predict the biological functions: they are found in proteins and enzymes with dissimilar functions.
Nonribosomal peptides (NRP) are a class of peptide secondary metabolites, usually produced by microorganisms like bacteria and fungi. Nonribosomal peptides are also found in higher organisms, such as nudibranchs, but are thought to be made by bacteria inside these organisms. While there exist a wide range of peptides that are not synthesized by ribosomes, the term nonribosomal peptide typically refers to a very specific set of these as discussed in this article.
UniProt is a freely accessible database of protein sequence and functional information, many entries being derived from genome sequencing projects. It contains a large amount of information about the biological function of proteins derived from the research literature. It is maintained by the UniProt consortium, which consists of several European bioinformatics organisations and a foundation from Washington, DC, United States.
Halobacterium is a genus in the family Halobacteriaceae.
A debranching enzyme is a molecule that helps facilitate the breakdown of glycogen, which serves as a store of glucose in the body, through glucosyltransferase and glucosidase activity. Together with phosphorylases, debranching enzymes mobilize glucose reserves from glycogen deposits in the muscles and liver. This constitutes a major source of energy reserves in most organisms. Glycogen breakdown is highly regulated in the body, especially in the liver, by various hormones including insulin and glucagon, to maintain a homeostatic balance of blood-glucose levels. When glycogen breakdown is compromised by mutations in the glycogen debranching enzyme, metabolic diseases such as Glycogen storage disease type III can result.
The bacterium, despite its simplicity, contains a well-developed cell structure which is responsible for some of its unique biological structures and pathogenicity. Many structural features are unique to bacteria and are not found among archaea or eukaryotes. Because of the simplicity of bacteria relative to larger organisms and the ease with which they can be manipulated experimentally, the cell structure of bacteria has been well studied, revealing many biochemical principles that have been subsequently applied to other organisms.
InterPro is a database of protein families, domains and functional sites in which identifiable features found in known proteins can be applied to new protein sequences in order to functionally characterise them.
Bactericidal/permeability-increasing protein (BPI) is a 456-residue (~50kDa) protein that is part of the innate immune system. It belongs to family of lipid-binding serum glycoproteins.
CD46 complement regulatory protein also known as CD46 and Membrane Cofactor Protein is a protein which in humans is encoded by the CD46 gene. CD46 is an inhibitory complement receptor.
Halobacterium salinarum is an extremely halophilic marine obligate aerobic archaeon. Despite its name, this is not a bacterium, but rather a member of the domain Archaea. It is found in salted fish, hides, hypersaline lakes, and salterns. As these salterns reach the minimum salinity limits for extreme halophiles, their waters become purple or reddish color due to the high densities of halophilic Archaea. H. salinarum has also been found in high-salt food such as salt pork, marine fish, and sausages. The ability of H. salinarum to survive at such high salt concentrations has led to its classification as an extremophile.
Halocins are bacteriocins produced by halophilic Archaea and a type of archaeocin.
60S ribosomal protein L17 is a protein that in humans is encoded by the RPL17 gene.
Anthony Edward Walsby, BSc(Birm), PhD(Lond), FRS, is the Emeritus Professor of Microbiology at the School of Biological Sciences, University of Bristol.
Haloferax volcanii is a species of organism in the genus Haloferax in the Archaea.
Halobacterium noricense is a halophilic, rod-shaped microorganism that thrives in environments with salt levels near saturation. Despite the implication of the name, Halobacterium is actually a genus of archaea, not bacteria. H. noricense can be isolated from environments with high salinity such as the Dead Sea and the Great Salt Lake in Utah. Members of the Halobacterium genus are excellent model organisms for DNA replication and transcription due to the stability of their proteins and polymerases when exposed to high temperatures. To be classified in the genus Halobacterium, a microorganism must exhibit a membrane composition consisting of ether-linked phosphoglycerides and glycolipids.
Gas vesicles, also known as gas vacuoles, are nanocompartments in certain prokaryotic organisms, which help in buoyancy. Gas vesicles are composed entirely of protein; no lipids or carbohydrates have been detected.
Shiladitya DasSarma is a molecular biologist well-known for contributions to the biology of halophilic and extremophilic microorganisms. He is a Professor in the University of Maryland Baltimore. He earned a PhD degree in Biochemistry from the Massachusetts Institute of Technology and a BS degree in Chemistry from Indiana University Bloomington. Prior to taking a faculty position, he conducted research at the Massachusetts General Hospital, Harvard Medical School, and Pasteur Institute, Paris.
Archaerhodopsin proteins are a family of retinal-containing photoreceptors found in the archaea genera Halobacterium and Halorubrum. Like the homologous bacteriorhodopsin (bR) protein, archaerhodopsins harvest energy from sunlight to pump H+ ions out of the cell, establishing a proton motive force that is used for ATP synthesis. They have some structural similarities to the mammalian GPCR protein rhodopsin, but are not true homologs.
References
- ↑ Walsby AE, Hayes PK (December 1989). "Gas vesicle proteins". Biochem. J. 264 (2): 313–22. doi:10.1042/bj2640313. PMC 1133585 . PMID 2513809.
- ↑ Englert C, Pfeifer F (May 1993). "Analysis of gas vesicle gene expression in Haloferax mediterranei reveals that GvpA and GvpC are both gas vesicle structural proteins". J. Biol. Chem. 268 (13): 9329–36. PMID 7683649.
- 1 2 UniProt, UniProt GvpA from halobacterium salinarum.
- ↑ Walsby AE (March 1994). "Gas vesicles". Microbiol. Rev. 58 (1): 94–144. doi:10.1128/mmbr.58.1.94-144.1994. PMC 372955 . PMID 8177173.
- ↑ Jones JG, Young DC, DasSarma S (June 1991). "Structure and organization of the gas vesicle gene cluster on the Halobacterium halobium plasmid pNRC100". Gene. 102 (1): 117–22. doi:10.1016/0378-1119(91)90549-Q. PMID 1864501.