Gram-negative bacteria component

Upopolysaccharides (14) are cell wall components of gram-negative bacteria. 

Currently, five different molecular classes of mdr efflux pumps are known [5], While pumps of the the ATP-binding cassette (ABC) transporter superfamily are driven by ATP hydrolysis, the other four superfamilies called resistance-nodulation-division (RND), major facilitator superfamily (MFS), multidrug and toxic compound extrusion (MATE), and small multidrag resistance transporter (SMR) are driven by the proton-motive force across the cytoplasmic membrane. Usually a single pump protein is located within the cytoplasmic membrane. However, the RND-type pumps which are restricted to Gram-negative bacteria consist of two additional components, a periplasmic membrane fusion protein (MFP) which connects the efflux pump to an outer... 

A lipopolysaccharide (LPS) is any compound consisting of covalently linked lipids and polysaccharides. The term is used more frequently to denote a cell wall component from Gram-negative bacteria. LPS has endotoxin activities and is a polyclonal stimulator of B-lymphocytes. 

A monoaminopentose, 4-amino-4-deoxy-L-arabinose, is known as a component of some Gram-negative bacteria. It is linked, as the )5-pyranosyl phosphate (18), to a 2-amino-2-deoxy-y -D-glucopyranosyI residue in the lipid A part of the LPS. ... 

A number of amide- and ester-linked fatty acids and (/ )-3-hydroxy acids are components of the lipid A part in the LPS from Gram-negative bacteria. The acids have been tabulatedand the chemistry of lipid A summarized. The most common acids in lipid A from Enterobacteriaceae are the saturated 12 0,14 0, and 16 0, and the (/ )-3-hydroxy-14 0, The last is linked to N-2 and 0-3 of the 2-amino-2-deoxy-D-glucopyranosyl residues, and the others are ester-linked to the hydroxy acid, as in the lipid A (44) of Salmonella minnesota. Other linear and branched fatty acids, unsaturated acids, S)-2- and (/ )-3-hydroxy acids, and 3-oxotetradecanoic acid are components of lipid A from certain different species. In the lipid A from Rhizobium trifolii, 2,7-dihydroxyoctanoic acid is linked as amide to a 2-amino-2-deoxy-D-gl ucopy ranosy 1 residue. ... 

C. trachomatis possesses characteristics resembling both bacteria and viruses. Its major membrane is comparable to that of gram-negative bacteria, although it lacks a peptidoglycan cell wall and requires cellular components from the host for replication. Chlamydia transmission risk is thought to be less than that of gonorrhea. 

In Gram-negative bacteria the cell wall is only about 3 nm thick, and located in the extended periplasmatic space between the inner membrane (IM) and an additional outer membrane (OM). The lipid monolayer in the outer leaflet of the OM contains about 90% lipopolysaccharides (LPS). LPS consist of Lipid A and an oligosaccharide component, which is highly specific for individual bacterial species and phenotypes [108, 114]. 

Figure 7.7 Structure of a generalized LPS molecule. LPS constitutes the major structural component of the outer membrane of Gram-negative bacteria. Although LPSs of different Gram-negative organisms differ in their chemical structure, each consists of a complex polysaccharide component, linked to a lipid component. Refer to text for specific details...

In Gram-negative bacteria which are characterised by a rather complex cell envelope, the CM is also referred to as inner membrane to distinguish it from a second lipid bilayer, termed outer membrane (OM). The space between these two layers is called the periplasm (PP). In the periplasmic space, many proteins are found with a variety of functions. Some are involved in biosynthesis and/or export of cell wall components and surface structures (e.g. pili, flagellae,... 

Lipid A constitutes the covalently bound lipid component and the least variable component of LPS (25). It anchors LPS to the bacterial cell by hydrophobic and electrostatic forces and mediates or contributes to many of the functions and activities that LPS exerts in prokaryotic and eukaryotic organisms. In the following sections, the primary structure of lipid A of different Gram-negative bacteria is described, together with some of its characteristic biological properties. Furthermore, this article describes some of the principal methods that have been used for the structural analysis of lipid A and discusses their merits and limitations. 

Some examples of transformations involving carbonyl ylides are listed in Table 4.20. Entry 1 illustrates the conversion of P-acyloxy-a-diazoesters into a-acyloxyacrylates by ring fission of a cyclic carbonyl ylide [978]. This reaction has been used for the synthesis of the natural aldonic acid KDO (3-deoxy-Z)-manno-2-octulosonic acid), which is an essential component of the cell wall lipopolysaccharide of gram-negative bacteria (Figure 4.15). 

Methanolic and ethyl acetate extracts of the fungus had low activity against a battery of Gram-positive and Gram-negative bacteria, but the isolated compound was not shown to be the active component. 

L-glycero-mannoheptose. The polysaccharide component of LPS may be divided into several structural domains. The inner (core) domains vary relatively little between LPS molecules isolated from different Gram-negative bacteria. The outer (O-specific) domain is usually bacterial strain-specific. 

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