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  • 1
    Electronic Resource
    Electronic Resource
    On the Origin of Operons and Their Possible Role in Evolution Toward Thermophily (1999)
    Springer
    Journal of molecular evolution 49 (1999), S. 432-438 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Operons — Thermophily — Last common ancestor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. We present a hypothesis suggesting that close linkage of functionally related anabolic genes and their ultimate integration into operons developed under selective pressure as a molecular strategy which contributed to the viability of ancestral thermophilic cells. Cotranslation of functionally related proteins is viewed as having facilitated the formation of multienzyme complexes channeling thermolabile substrates and the mutual stabilization of inherently thermolabile proteins. In this perspective, the evolutionary scheme considered the most probable is the evolution of both Bacteria and Archaea by thermoreduction (Forterre 1995) from a mesophilic, protoeukaryotic last common ancestor (LCA) endowed with appreciable genetic redundancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006566
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  • 2
    Electronic Resource
    Electronic Resource
    The Evolutionary History of Carbamoyltransferases: A Complex Set of Paralogous Genes Was Already Present in the Last Universal Common Ancestor (1999)
    Springer
    Journal of molecular evolution 49 (1999), S. 461-473 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Carbamoyltransferases — ATCase — OTCase — Protein evolution — Gene duplication — Paralogous proteins — Last universal common ancestor — Molecular phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Forty-four sequences of ornithine carbamoyltransferases (OTCases) and 33 sequences of aspartate carbamoyltransferases (ATCases) representing the three domains of life were multiply aligned and a phylogenetic tree was inferred from this multiple alignment. The global topology of the composite rooted tree (each enzyme family being used as an outgroup to root the other one) suggests that present-day genes are derived from paralogous ancestral genes which were already of the same size and argues against a mechanism of fusion of independent modules. A closer observation of the detailed topology shows that this tree could not be used to assess the actual order of organismal descent. Indeed, this tree displays a complex topology for many prokaryotic sequences, with polyphyly for Bacteria in both enzyme trees and for the Archaea in the OTCase tree. Moreover, representatives of the two prokaryotic Domains are found to be interspersed in various combinations in both enzyme trees. This complexity may be explained by assuming the occurrence of two subfamilies in the OTCase tree (OTC α and OTC β) and two other ones in the ATCase tree (ATC I and ATC II). These subfamilies could have arisen from duplication and selective losses of some differentiated copies during the successive speciations. We suggest that Archaea and Eukaryotes share a common ancestor in which the ancestral copies giving the present-day ATC II/OTC β combinations were present, whereas Bacteria comprise two classes: one containing the ATC II/OTC α combination and the other harboring the ATC I/OTC β combination. Moreover, multiple horizontal gene transfers could have occurred rather recently amongst prokaryotes. Whichever the actual history of carbamoyltransferases, our data suggest that the last common ancestor to all extant life possessed differentiated copies of genes coding for both carbamoyltransferases, indicating it as a rather sophisticated organism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006569
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  • 3
    Electronic Resource
    Electronic Resource
    Studies on the central metabolism of Thermus aquaticus, an extreme thermophilic bacterium: Anaplerotic reactions and their regulation (1981)
    Springer
    Archives of microbiology 129 (1981), S. 173-177 
    Details
    ISSN: 1432-072X
    Keywords: Extreme thermophile ; Thermus aquaticus ; Metabolic regulation ; Anaplerotic pathways
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The physiology of Thermus aquaticus strain Z05 was investigated. Substantial evidence for gene and enzyme regulation in the central metabolism of this extreme thermophile was found. Two anaplerotic pathways were detected: (1) phosphoenolpyruvate carboxylase; (2) a glyoxylate shunt which proved to be essential for growth on pyruvate as well as acetate. The synthesis of isocitrate lyase and malate synthase were found to depend on a common control mechanism. Pronounced regulatory effects were observed on the activity of malic enzyme, pyruvate kinase and phosphoenolpyruvate carboxylase. The data could be fitted together into a picture of the metabolism during glycolysis and gluconeogenesis which shows how variations of enzyme levels and activities correlate with the apparent needs of the cell. Our results call attention to a peculiar metabolic analogy between T. aquaticus and Acinetobacter
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00455357
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  • 4
    Electronic Resource
    Electronic Resource
    A comparative analysis of extreme thermophilic bacteria belonging to the genus Thermus (1978)
    Springer
    Archives of microbiology 117 (1978), S. 189-196 
    Details
    ISSN: 1432-072X
    Keywords: Thermus aquaticus ; Thermus thermophilus ; Extreme thermophiles ; Growth media ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several extreme thermophilic Gram negative bacteria found in a thermally polluted river in Belgium have been compared with Thermus strains isolated from widely distant geographical areas. This analysis has become possible after the design of a new culture medium (162). All strains examined (including the isolate successively denominated Flavobacterium thermophilum and Thermus thermophilus) were found to be morphologically identical with strain YT-1 of Thermus aquaticus. The cells are immotile, rod-like, strictly aerobic, catalase and oxidase positive. They produce amylase, hydrolyze gelatin and are confirmed to be highly sensitive towards penicillin. The nutritional pattern of all strains has been analysed extensively, by testing a broad spectrum of possible substrates. The strains display a uniform response to the microbiological tests applied and most probably belong to the same species: Thermus aquaticus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00402307
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  • 5
    Electronic Resource
    Electronic Resource
    The highly thermostable arginine repressor of Bacillus stearothermophilus: gene cloning and repressor–operator interactions (1997)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 25 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We report here the cloning of the arginine repressor gene argR of Bacillus stearothermophilus and the characterization and purification to homogeneity of its product. The deduced amino acid sequence of the 16.8-kDa ArgR subunit shares 72% identity with its mesophilic homologue AhrC of Bacilus subtilis. Sequence analysis of B. stearothermophilus ArgR and comparisons with mesophilic arginine repressors suggest that the thermostable repressor comprises an N-terminal DNA-binding and a C-terminal oligomerization and arginine-binding region. B. stearothermophilus ArgR has been overexpressed in E. coli and purified as a 48.0-kDa trimeric protein. The repressor inhibits the expression of a B. stearothermophilus argC–lacZ fusion in E. coli cells. In the presence of arginine, the purified protein binds tightly and specifically to the argC operator, which largely overlaps the argC promoter. The purified B. stearothermophilus repressor proved to be very thermostable with a half-life of approximately 30 min at 90°C, whereas B. subtilis AhrC was largely inactivated at 65°C. Moreover, ArgR operator complexes were found to be remarkably thermostable and could be formed efficiently at up to 85°C, well above the optimal growth temperature of the moderate thermophile B. stearothermophilus. This pronounced resistance of the repressor–operator complexes to heat treatment suggests that the same type of regulatory mechanism could operate in extreme thermophiles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.4781845.x
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  • 6
    Electronic Resource
    Electronic Resource
    High resolution contact probing of the Lrp-like DNA-binding protein Ss-Lrp from the hyperthermoacidophilic crenarchaeote Sulfolobus solfataricus P2 (2002)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 45 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Ss-Lrp, from Sulfolobus solfataricus, is an archaeal homologue of the global bacterial regulator Lrp (Leucine-responsive regulatory protein), which out of all genome-encoded proteins is most similar to Escherichia coli Lrp (E-value of 5.6 e−14). The recombinant protein has been purified as a 68 kDa homotetramer. The specific binding of Ss-Lrp to its own control region is suggestive of negative autoregulation. A high resolution contact map of Ss-Lrp binding was established by DNase I and hydroxyl radical footprinting, small non-intercalating groove-specific ligand-binding interference, and various base-specific premodification and base removal binding interference techniques. We show that Ss-Lrp binds one face of the DNA helix and establishes the most salient contacts with two major groove segments and the intervening minor groove, in a region that overlaps the TATA-box and BRE promoter elements. Therefore, Ss-Lrp most likely exerts autoregulation by preventing promoter recognition by TBP and TFB. Moreover, the results demonstrate profound Ss-Lrp induced structural alterations of sequence stretches flanking the core contact site, and reveal that the deformability of these regions significantly contributes to binding selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.03136.x
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  • 7
    Electronic Resource
    Electronic Resource
    Structure of the arginine repressor from Bacillus stearothermophilus (1999)
    [s.l.] : Nature America Inc.
    Nature structural biology 6 (1999), S. 427-432 
    Details
    ISSN: 1072-8368
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The arginine repressor (ArgR) is a hexameric DNA-binding protein that plays a multifunctional role in the bacterial cell. Here, we present the 2.5 Å structure of apo-ArgR from Bacillus stearothermophilus and the 2.2 Å structure of the hexameric ArgR oligomerization domain with bound ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/8229
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  • 8
    Electronic Resource
    Electronic Resource
    The arginine operon ofBacillus stearothermophilus: characterization of the control region and its interaction with the heterologousB. subtilis arginine repressor (1996)
    Springer
    Molecular genetics and genomics 252 (1996), S. 69-78 
    Details
    ISSN: 1617-4623
    Keywords: Bacillus stearothermophilus argC gene sequence ; Operator ; Arginine repressor ; Gene regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mechanisms of gene regulation have not yet been extensively studied in thermophilic bacteria. In previous studies we showed that theBacillus stearothermophilus argCJBD gene cluster is subject to specific repression by arginine. Here we report the cloning by colony hybridization, and characterization of the proximal part of theargC gene together with the adjacent control region of the cluster. The promoter was identified by primer extension mapping of theargC transcription startpoint: a sequence overlapping it was found to be similar to the arginine operators ofB. subtilis and to a smaller extent ofE. coli. Use of anargC-lacZ gene fusion revealed that theargC promoter is strongly repressed by the heterologousB. subtilis arginine repressor/activator AhrC inE. coli cells. Mobility shift and DNase I footprinting experiments revealed tight, specific and arginine-dependent binding of this operator-like sequence to purified AhrC. It is there-fore very likely that inB. stearothermophilus the expression of theargCJBD operon is modulated by a repressor that is the thermophilic homologue of AhrC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02173206
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  • 9
    Electronic Resource
    Electronic Resource
    The arginine operon of Bacillus stearothermophilus: characterization of the control region and its interaction with the heterologous B. subtilis arginine repressor (1996)
    Springer
    Molecular genetics and genomics 252 (1996), S. 69-78 
    Details
    ISSN: 1617-4623
    Keywords: Key wordsBacillus stearothermophilus argC gene sequence ; Operator ; Arginine repressor ; Gene regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mechanisms of gene regulation have not yet been extensively studied in thermophilic bacteria. In previous studies we showed that the Bacillus stearothermophilus argCJBD gene cluster is subject to specific repression by arginine. Here we report the cloning by colony hybridization, and characterization of the proximal part of the argC gene together with the adjacent control region of the cluster. The promoter was identified by primer extension mapping of the argC transcription startpoint: a sequence overlapping it was found to be similar to the arginine operators of B. subtilis and to a smaller extent of E. coli. Use of an argC-lacZ gene fusion revealed that the argC promoter is strongly repressed by the heterologous B. subtilis arginine repressor/activator AhrC in E. coli cells. Mobility shift and DNase I footprinting experiments revealed tight, specific and arginine-dependent binding of this operator-like sequence to purified AhrC. It is therefore very likely that in B. stearothermophilus the expression of the argCJBD operon is modulated by a repressor that is the thermophilic homologue of AhrC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004389670008
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  • 10
    Electronic Resource
    Electronic Resource
    Mutation of gene encoding regulatory polypeptide of aspartate carbamoyltransferase (1981)
    [s.l.] : Nature Publishing Group
    Nature 292 (1981), S. 370-373 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] ATCase catalyses the first reaction specific to pyrimidine biosynthesis, the formation of JV-carbamoyl-L-aspartate from L-aspartate and carbamoylphosphate. In E. coli, ATCase activity is modulated by feedback inhibition by CTP, the end product of the pyrimidine pathway, and activation by ATP, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/292370a0
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