Halobacterial glycoprotein biosynthesis.
TL;DR: The structure of the saccharides linked to the cell surface giycoprotein and the role of glycopeptides in this study have been studied to provide an understanding of their role in inflammation.
About: This article is published in Biochimica et Biophysica Acta.The article was published on 1987-04-27 and is currently open access. It has received 109 citations till now. The article focuses on the topics: Halobacterium & Flagellin.
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TL;DR: Regardless of the type of motility machinery that is employed, most motile microorganisms use complex sensory systems to control their movements in response to stimuli, which allows them to migrate to optimal environments.
Abstract: Prokaryotic cells move through liquids or over moist surfaces by swimming, swarming, gliding, twitching or floating. An impressive diversity of motility mechanisms has evolved in prokaryotes. Movement can involve surface appendages, such as flagella that spin, pili that pull and Mycoplasma 'legs' that walk. Internal structures, such as the cytoskeleton and gas vesicles, are involved in some types of motility, whereas the mechanisms of some other types of movement remain mysterious. Regardless of the type of motility machinery that is employed, most motile microorganisms use complex sensory systems to control their movements in response to stimuli, which allows them to migrate to optimal environments.
527 citations
TL;DR: Thecrystalline arrays of proteinaceous subunits forming surface layers reveal a broad-application potential in biotechnology, vaccine development and molecular nanotechnology.
Abstract: Crystalline arrays of proteinaceous subunits forming surface layers (S-layers) are one of the most commonly observed prokaryotic cell envelope structures. They are ubiquitous amongst Gram-positive and Gram-negative archeaobacteria and eubacteria and, if present, account for the major protein species produced by the cells. S-layers can provide organisms with a selection advantage by providing various functions including protective coats, molecular sieves, ion traps and structures involved in cell surface interactions. S-layers were identified as contributing to virulence when present as a structural component of pathogens. In Gram-negative archaeobacteria they are involved in determining cell shape and cell division. The crystalline arrays reveal a broad-application potential in biotechnology, vaccine development and molecular nanotechnology.
450 citations
TL;DR: Thecrystalline arrays of proteinaceous subunits forming surface layers reveal a broad‐application potential in biotechnology, vaccine development and molecular nanotechnology.
Abstract: Publisher Summary Prokaryotic cells have developed different ways to present their surfaces to the environment. One of the most remarkable features of many Gram-positive and Gram-negative eubacteria and archaebacteria is the presence of a regularly ordered protein or glycoprotein layer as the outermost component of the cell envelope, called the surface layer (S-layer). They are composed of a single molecular species, protein or glycoprotein in nature, and are endowed with the ability to assemble into 2D crystalline arrays by an entropy-driven process. S-layers possess a high degree of structural regularity, and thus they are the most abundant of all bacterial cellular proteins, they are ideal model systems for studying the dynamic process of assembly of a supramolecular structure during cell growth. S-Layers are the simplest biological protein membranes developed during evolution. The information encoded in a single S-layer protein species guarantees maintenance of a closed, highly ordered porous protein meshwork on a growing cell surface. Surface layers are an integral part of the cell envelope of a great variety of archaebacteria and eubacteria. Because of their surface location, it is evident that functions have evolved as the result of specific interactions with particular environmental and ecological conditions. Due to the increased knowledge of the structure, assembly, chemistry, biosynthesis, pathogenicity and permeability properties of S-layers, a considerable potential for various biotechnological and non-biological applications for 2D crystals have become evident in few years.
257 citations
TL;DR: The structural requirements for the extraordinary stability of many S- layer proteins, the structural and functional aspects of the S-layer homology domain found in S-layers, extracellular enzymes and related functional proteins, and outer membrane proteins,and the molecular interactions of S- Layer proteins with other cell wall components are discussed.
239 citations
TL;DR: The overall structure of the cell surface glycoprotein of halobacteria is thus reminiscent of animal proteoglycans and a functional role of the glycosaminoglycan chain in maintaining the rod shape of Halob bacteria is discussed.
Abstract: Abstract Glycoproteins as components of cell surfaces are not restricted to eukaryotes. The prokaryotic glycoprotein studied in greatest detail so far is the cell surface glycoprotein of the archaebacterium Halobacterium halobium . This bacterial glycoprotein contains 3 different types of glycoconjugates, and each type of glycoconjugate involves a different carbohydrate-protein linkage unit: 1. 1) One glycosaminoglycan chain, constructed from a repeating sulfated pentasaccharide block, is linked to one protein molecule via the novel N -glycosyl linkage unit asparaginyl- N -acetylgalactosamine. 2. 2) Ten sulfated oligosaccharides that contain glucose, glucuronic acid and iduronic acid are bound to the protein via the hitherto unknown N -glycosyl linkage unit asparaginylglucose. 3. 3) About 15 disaccharides, glucosylgalactose, are O -glycosyl-linked to a cluster of threonine residues close to the C-terminus of the core protein. The overall structure of the cell surface glycoprotein of halobacteria is thus reminiscent of animal proteoglycans and a functional role of the glycosaminoglycan chain in maintaining the rod shape of halobacteria is discussed. Biosynthesis of the two N -glycosyl linkage units involves dolichol monophosphate and dolicholdiphosphate-linked saccharide precursors. Sulfation and epimerization of the glycoconjugates occur at the lipid-linked level and the mature saccharides are transferred to the protein core on the cell surface. The sulfated oligosaccharides that finally become bound to asparagine via glucose are transiently methylated at their lipid-linked stage and this transient chemical modification seems to be required for the biosynthesis of the corresponding N -glycosyl bond.
235 citations
References
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TL;DR: The structure of ASPARAGINE-LINKed OLIGOSACCI-IARIDES and transfer-Oligosaccharide Structural Requirements, and Sequence of Processing and Specificity of Processing Enzymes are presented.
Abstract: PERSPECTIVES AND SUMMARY 631 STRUCTURES OF ASPARAGINE-LINKED OLIGOSACCI-IARIDES 632 ASSEMBLY AND TRANSFER OF THE LIPID-LINKED OLIGOSACCHARIDE ...... 635 Assembly 635 Transfer-Oligosaccharide Structural Requirements 636 Transfer-Role of Peptide Acceptor 637 OLIGOSACCHARIDE P OCESSING 639 Sequence of Processing 639 Subcellular Localization of Processing Enzymes 641 Processing in Lower Organisms 643 Specificity of Processing Enzymes 644 OTHER POS’VI~RANSLATIONAL MODIFICATIONS 653 CONTROL F OLIGOSACCHARIDE PROCESSING 655
4,699 citations
TL;DR: The glycoprotein which accounts for approximately 50% of the protein and all of the nonlipid carbohydrate of the cell envelope of Halobacterium salinarium has been purified and partially characterized and shows the first report of either type of linkage in a prokaryotic cell envelope protein.
280 citations
TL;DR: The various results indicate an absolute requirement for a hydrogen-bond-donor function in the side chain of the hydroxy amino acid of the "marker sequence" and point to a considerable influence of the structure of this amino acid on binding as well as on the glycosyl transfer itself.
Abstract: The catalytical role of the hydroxy amino acid in the "marker sequence" Asn-Xaa-Thr(Ser) for the N-glycosylation step of glycoprotein formation was investigated by using a series of hexapeptides derived from Tyr-Asn-Gly-Xaa-Ser-Val by substituting threonine, serine, cysteine, valine and O-methylthreonine respectively for Xaa. The results, which were obtained with calf liver microsomal fractions as enzyme source and dolichyl diphosphate di-N-acetyl [14C] chitobiose as glycosyl donor showed that the threonine-, serine- and cysteine-containing derivatives could be glycosylated, although at very different rates, whereas the valine and O-methylthreonine analogues did not work as glycosyl acceptors. Replacement of threonine by serine resulted in a 4-fold decrease in Vmax, and about a 10-fold increase in Km for glycosyl transfer. Replacement of serine by cysteine again decreased acceptor activity 2-3-fold. The various results, taken together, indicate an absolute requirement for a hydrogen-bond-donor function in the side chain of the hydroxy amino acid of the "marker sequence" and furthermore, point to a considerable influence of the structure of this amino acid on binding as well as on the glycosyl transfer itself. In order to explain the observed differences in the glycosyl-transfer rates, a model is proposed with a hydrogen-bond interaction between the amide of asparagine as the hydrogen-bond donor and the oxygen of the hydroxy group of the hydroxy amino acid as the hydrogen-bond acceptor. The participation of the hydroxy group in the catalytic mechanism of glycosyl transfer in the kind of proton-relay system is discussed.
229 citations
TL;DR: Rotation of tethered cells demonstrates that Halobacteria move due to the rotation of the flagella, which is significant for halobacteria to swim forward and backwards by counterclockwise rotation of their flagellar bundle.
214 citations
TL;DR: Improved fixation techniques clearly show a cell wall-like structure on the surface of these cells, and the easily sedimentable residue that remains after lysis of the cells or envelopes in distilled water also contains "intracytoplasmic membranes" with unusual structural characteristics.
Abstract: The reported absence of a cell wall in halobacteria cannot be confirmed. Improved fixation techniques clearly show a cell wall-like structure on the surface of these cells. A stepwise reduction of the salt concentration causes the release of cell wall material before the cell membrane begins to disintegrate. The cell membrane breaks up into fragments of variable but rather small size, which are clearly different from a 4S component reported by others to be the major breakdown product of the cell membrane. It appears more likely that the 4S component arises from the dissolution of the cell wall. A residue of large membranous sheets remains even after prolonged exposure of halobacteria envelopes to distilled water. The lipids in these sheets do not differ significantly from the lipids in the lysed part of the cell membrane. The sheets, however, contain a purple-colored substance, which is not present in the lysed part. The easily sedimentable residue that remains after lysis of the cells or envelopes in distilled water also contains "intracytoplasmic membranes" with unusual structural characteristics. They can also be identified in sections through intact bacteria or envelope preparations. Their function is at present unknown but seems to be related to the formation of gas vacuoles in these organisms.
198 citations