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  • 1
    ISSN: 1432-1432
    Keywords: Evolution ; Multiple sequence alignment ; NTP binding ; Phylogenetic analysis ; Positive-strand RNA viruses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary NTP-motif, a consensus sequence previously shown to be characteristic of numerous NTP-utilizing enzymes, was identified in nonstructural proteins of several groups of positive-strand RNA viruses. These groups include picorna-, alpha-, and coronaviruses infecting animals and como-, poty-, tobamo-, tricorna-, hordei-, and furoviruses of plants, totalling 21 viruses. It has been demonstrated that the viral NTP-motif-containing proteins constitute three distinct families, the sequences within each family being similar to each other at a statistically highly significant level. A lower, but still valid similarity has also been revealed between the families. An overall alignment has been generated, which includes several highly conserved sequence stretches. The two most prominent of the latter contain the socalled “A” and “B” sites of the NTP-motif, with four of the five invariant amino acid residues observed within these sequences. These observations, taken together with the results of comparative analysis of the positions occupied by respective proteins (domains) in viral multidomain proteins, suggest that all the NTP-motif-containing proteins of positive-strand RNA viruses are homologous, constituting a highly diverged monophyletic group. In this group the “A” and “B” sites of the NTP-motif are the most conserved sequences and, by inference, should play the principal role in the functioning of the proteins. A hypothesis is proposed that all these proteins posses NTP-binding capacity and possibly NTPase activity, performing some NTP-dependent function in viral RNA replication. The importance of phylogenetic analysis for the assessment of the significance of the occurrence of the NTP-motif (and of sequence motifs of this sort in general) in proteins is emphasized.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 34 (1992), S. 351-357 
    ISSN: 1432-1432
    Keywords: Primase-helicase systems ; Evolution ; Bacteria ; Bacteriophage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Amino acid sequences of primases and associated helicases involved in the DNA replication of eubacteria and bacteriophages T7, T3, T4, P4, and P22 were compared by computer-assisted methods. There are two types of such systems, the first one represented by distinct helicase and primase proteins (e.g., DnaB and DnaG proteins of Escherichia coli), and the second one by single polypeptides comprising both activities (gp4 of bacteriophages T7 and T3, and alpha protein of bacteriophage P4). Pronounced sequence similarity was revealed between approximately 250 amino acid residue N-terminal domains of stand-alone primases and the primase-helicase proteins of T7(T3) and P4. All these domains contain, close to their N-termini, a conserved Zn-finger pattern that may be implicated in template DNA recognition by the primases. In addition, they encompass five other conserved motifs some of which may be involved in substrate (NTP) binding. Significant similarity was also observed between the primase-associated helicases (DnaB, gp12 of P22 and gp41 of T4) and the C-terminal domain of T7(T3) gp4. On the other hand the C-terminal domain of P-alpha of P4 is related to another group of DNA and RNA helicases. Tentative phylogenetic trees generated for the primases and the associated helicases showed no grouping of the phage proteins, with the exception of the primase domains of bacteriophages T4 and P4. This may indicate a common origin for one-component primase-helicase systems. Two scenarios for the evolution of primase-helicase systems are discussed. The first one involves fusion of the primase and helicase components (T7 and T3) or fusion of the primase component with a different type of helicase domain (P4). The second possibility is the duplication of an ancestral gene encoding a gp4-like bifunctional protein followed by divergence of the copies, one of which retains the primase and the other the helicase domain.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 45 (1997), S. 117 -118 
    ISSN: 1432-1432
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 48 (1999), S. 291-302 
    ISSN: 1432-1432
    Keywords: Key words: RNA-binding domains — Ribosomal protein S4 — Archaeosine transglycosylase — Pseudouridine synthase — Translation machinery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Two previously undetected domains were identified in a variety of RNA-binding proteins, particularly RNA-modifying enzymes, using methods for sequence profile analysis. A small domain consisting of 60–65 amino acid residues was detected in the ribosomal protein S4, two families of pseudouridine synthases, a novel family of predicted RNA methylases, a yeast protein containing a pseudouridine synthetase and a deaminase domain, bacterial tyrosyl-tRNA synthetases, and a number of uncharacterized, small proteins that may be involved in translation regulation. Another novel domain, designated PUA domain, after PseudoUridine synthase and Archaeosine transglycosylase, was detected in archaeal and eukaryotic pseudouridine synthases, archaeal archaeosine synthases, a family of predicted ATPases that may be involved in RNA modification, a family of predicted archaeal and bacterial rRNA methylases. Additionally, the PUA domain was detected in a family of eukaryotic proteins that also contain a domain homologous to the translation initiation factor eIF1/SUI1; these proteins may comprise a novel type of translation factors. Unexpectedly, the PUA domain was detected also in bacterial and yeast glutamate kinases; this is compatible with the demonstrated role of these enzymes in the regulation of the expression of other genes. We propose that the S4 domain and the PUA domain bind RNA molecules with complex folded structures, adding to the growing collection of nucleic acid-binding domains associated with DNA and RNA modification enzymes. The evolution of the translation machinery components containing the S4, PUA, and SUI1 domains must have included several events of lateral gene transfer and gene loss as well as lineage-specific domain fusions.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 8 (1993), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 24 (1997), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 204 (2001), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 203 (2001), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The archetypal two-component signal transduction systems include a sensor histidine kinase and a response regulator, which consists of a receiver CheY-like domain and a DNA-binding domain. Sequence analysis of the sensor kinases and response regulators encoded in complete bacterial and archaeal genomes revealed complex domain architectures for many of them and allowed the identification of several novel conserved domains, such as PAS, GAF, HAMP, GGDEF, EAL, and HD-GYP. All of these domains are widely represented in bacteria, including 19 copies of the GGDEF domain and 17 copies of the EAL domain encoded in the Escherichia coli genome. In contrast, these novel signaling domains are much less abundant in bacterial parasites and in archaea, with none at all found in some archaeal species. This skewed phyletic distribution suggests that the newly discovered complexity of signal transduction systems emerged early in the evolution of bacteria, with subsequent massive loss in parasites and some horizontal dissemination among archaea. Only a few proteins containing these domains have been studied experimentally, and their exact biochemical functions remain obscure; they may include transformations of novel signal molecules, such as the recently identified cyclic diguanylate. Recent experimental data provide the first direct evidence of the participation of these domains in signal transduction pathways, including regulation of virulence genes and extracellular enzyme production in the human pathogens Bordetella pertussis and Borrelia burgdorferi and the plant pathogen Xanthomonas campestris. Gene-neighborhood analysis of these new domains suggests their participation in a variety of processes, from mercury and phage resistance to maintenance of virulence plasmids. It appears that the real picture of the complexity of phosphorelay signal transduction in prokaryotes is only beginning to unfold.
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 209 (2002), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The lipoyl-binding domain is often present, in one or several copies, in the E2 subunit and, less often, in the E1 and E3 subunits of 2-oxo acid dehydrogenase complexes. Phylogenetic analysis shows evidence of multiple, independent intragenomic recombination events between different versions of the lipoyl-binding domain in various bacteria and eukaryotic mitochondria, leading to homogenization of the sequences of the lipoyl-binding domain within the same enzymatic complex in several bacterial lineages. This appears to be the first case of sequence homogenization at the level of an individual domain in prokaryotes.
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 227 (2003), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Aconitase, an essential enzyme of the tricarboxylic acid cycle (TCA), so far has been identified only in a minority of archaeal genomes. This enzyme belongs to the aconitase A family, which is represented in most bacteria and eukaryotes. Using iterative sequence database search, we linked two previously uncharacterized protein families (COG1679 and COG1786), respectively, to the three Fe–S-cluster-associated aconitase domains and the swiveling domain, the four domains that are present in all known aconitase families. The respective genes are often found in one predicted operon and, moreover, are fused in several species, suggesting a functional and physical interaction. We predict that these proteins together comprise a previously undetected, distinct aconitase family, which we designated aconitase X. Aconitase X is encoded in the genomes of many archaea and some proteobacteria. Among archaea, the pattern of aconitase X occurrence complements that of aconitase A such that together the two enzymes account for aconitase activity in all archaea. Phylogenetic analysis indicates that aconitase X is likely to be the ancestral archaeal form, with non-orthologous displacement in some of the archaea apparently brought about by horizontal transfer of the gene for bacterial aconitase A. The prediction of aconitase X completes the TCA cycle for Methanothermobacter thermoautotrophicus and Archaeoglobus fulgidus and suggests that most archaea have a full TCA cycle.
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