Archaeobacteria

Finally, besides conventional liposomes that are made from natural (e.g., egg yolk and soybean) or synthetic phospholipids, novel liposomes called archaeosomes that are prepared from the polar ether lipids extracted from various archaeobacteria proved also interesting for the design of vaccines as peptide antigen carriers (71) and as powerful self-adjuvanting vaccine delivery vesicles that promote both humoral and cell-mediated immunity (72). Related to this, one can mention that pseudopeptides, which are less prone to proteolysis when conjugated to liposomes, were also competent in triggering a humoral immune response (73). 

Conlan JW, et al. Immunization of mice with lipopeptide antigens encapsulated in novel liposomes prepared from the polar lipids of various Archaeobacteria elicits rapid and prolonged specific protective immunity against infection with the facultative intracellular pathogen. Listeria monocytogenes. Vaccine 2001 19 3509. 

Clarke KJ, Finlay BJ, Esteban G, Guhl BE, Embley TM (1993) Cyclidium porcatum N. sp. -a free-living anaerobic scuticociliate containing a stable complex of hydrogenosomes, eubacteria and archaeobacteria. Eur J Protistol 29 262-270 Corliss JO (1979) The ciliated protozoa Characterization, classification, and guide to the literature. Pergamon Press, London... 

A related anchor that uses diphytanylglycerylation is found in certain proteins of archaeobacteria.216... 

Archaeobacteria 7, 815 Area detector for X-rays 134 Arg-Gly-Asp (RGD) sequence 408 Arginase 888... 

Some thermophilic archaeobacteria are able to live with C02 as their sole source of carbon and reduction of elemental sulfur with H2 (Eq. 18-33) as their sole source of energy.368 369... 

Initiator tRNAs. While the T /C sequence has been found in all bacterial and most eukaryotic tRNAs examined, it is replaced by UCG in eukaryotic initiator tRNAs. In these tRNAs the preceding two nucleotides, beginning in the stem of loop IV, are also conserved the complete conserved sequence being GAUCG.184 Other characteristics of initiator tRNAs are the absence of base-pairing between residues 1, and 72, and the presence of C rather than G at position 1, A rather than G at position 72, and CCU in place of the two dihydroU residues in loop I.185 Initiator tRNAs of chloroplasts resemble those of bacteria,186 whereas archaeobacteria have their own unique peculiarities.187 These include the presence of a hypermod-ified base known as archaeosine (p. 1456) in position 15 of the dihydroU loop.188 189... 

Examination of the complete genome sequences of methanogens revealed an apparent lack of cysteinyl-tRNA synthetase. However, prolyl-tRNA synthetase does correctly aminoacylate the tRNAs for both proline and cysteine in these archaeobacteria.271 272a... 

Factor EF-G from eukaryotes (eEF2) is similar to the bacterial protein, but its interaction with the larger eukaryotic ribosomes seems to be more complex. For example, interaction with the ribosomal stalk is more extensive.37 EF2 contains a single modified histidine called diphthamide.397 This amino acid is not found in other proteins but is always present in eukaryotic EF2 and also in EF-G from archaeobacteria. It is the site of modification by diphtheria toxin (Box 29-A). 

The last initiation step (step/. Fig. 29-11) is the reaction of the 60S ribosomal subunit with the 48S initiation complex to form the SOS initiation complex. Initiation factors 3,4C, the eIF2 GDP complex, and inorganic phosphate are all released in this process, which is promoted by IF5. This monomeric 60-kDa protein " also stimulates conversion of the GTP bound to IF2 into GDP and Pj. IF5 is unique as the only known protein containing hypusine, -(4-amino-2-hydroxybutyl)lysine, a posttranslationally modified lysine. It occurs only at position 50 in the 17-kDa protein. " Hypusine is not present in eubacte-ria but is essential for viability of both eukaryotes and archaeobacteria and is present within an invariant... 

Archaeobacteria Prokaryotic organisms lacking peptidoglycan in their cell walls and differing from eubacteria in many ways. 

Halobacteria One of the groups of the archaeobacteria that lives in very concentrated salt environments. 

The term Archaea is currently preferred to Archaebacteria, Archaeobacteria, Archebacteria or Archeobacteria, but all five terms can be found in the literature. 

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