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  • 1
    Electronic Resource
    Electronic Resource
    The phosphotriesterase gene opdA in Agrobacterium radiobacter P230 is transposable (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 222 (2003), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We report a transposase gene (tnpA) upstream of the opdA phosphotriesterase gene of Agrobacterium radiobacter P230, as well as inverted repeats indicative of insertion sequences, flanking the two genes. Both the tnpA gene and the inverted repeats resemble the Tn610 transposon from Mycobacterium fortuitum. Two additional putative open reading frames separate opdA and tnpA with inferred translation products with similarity to two proteins encoded on the Geobacillus stearothermophilus IS5376 transposon. To test the proposition that these genes were contained on a transposon, an artificial composite transposon was constructed. This artificial transposon was then delivered into Escherichia coli DH10β cells. Transposition was demonstrated by the presence of opdA on the E. coli chromosome and confirmation of insertion by inverse polymerase chain reaction. The data presented suggest a possible role of transposition in the distribution of the opd/opdA genes across a wide range of soil bacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0378-1097(03)00211-8
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  • 2
    Electronic Resource
    Electronic Resource
    Isolation of a Pseudomonas monteilli strain with a novel phosphotriesterase (2002)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 206 (2002), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A Pseudomonas monteilli strain (designated C11) that uses the phosphotriester coroxon as its sole phosphorus source has been isolated. Native PAGE and activity staining identified a single isozyme with significant phosphotriesterase activity in the soluble fraction of the cell. This phosphotriesterase could hydrolyse both coumaphos and coroxon. The hydrolysis product of coroxon, diethylphosphate, and the thion analogue, coumaphos, could not serve as phosphorus sources when added to the growth medium. The majority of the phosphotriesterase and phosphatase activity was contained in the soluble fraction of the cell. Phosphatase activity was inhibited by vanadate as well as by dialysis against the metal chelator, EDTA. Phosphotriesterase activity was not affected by either vanadate or dialysis with EDTA or 1,10-phenanthroline. Phosphotriesterase activity was regulated by the amounts of both phosphate and coroxon in the medium, whereas total phosphatase activity was regulated by phosphate but not coroxon. A lack of hybridisation using a probe against the opd (organophosphate degradation) gene encoding a phosphotriesterase from Flavobacterium sp. ATCC27551 against bulk DNA from P. monteilli C11 suggested that this strain does not contain opd. The work presented here indicates the presence of a novel phosphotriesterase in P. monteilli C11.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2002.tb10985.x
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  • 3
    Electronic Resource
    Electronic Resource
    Reconstructing the Diversification of α-Esterases: Comparing the Gene Clusters of Drosophila buzzatii and D. melanogaster (2000)
    Springer
    Journal of molecular evolution 51 (2000), S. 149-160 
    Details
    ISSN: 1432-1432
    Keywords: Key words:Drosophila— Gene duplications — Carboxyl/cholinesterases — Phylogeny — Tertiary structure — Evolutionary rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. A cluster composed of 10 active α-esterase genes and a pseudogene is distributed over 60 kb in the Drosophila melanogaster genome. This paper describes the corresponding cluster in Drosophila buzzatii, whose lineage diverged from that of D. melanogaster when the subgenera Drosophila and Sophophora diverged about 50 Mya. With three exceptions we find that the composition of the cluster is conserved in the two lineages. The location of αE1 in D. melanogaster differs from that of its nearest relative in D. buzzatii, and αE4 has duplicated independently in the two lineages. The nature of these differences indicates that a mechanism exists whereby copies of genes can be placed in opposite orientation and nonadjacent positions within a gene cluster, although this does not seem to be a feature of earlier events in the cluster's evolution. The rates of amino acid change are not significantly different between orthologs, but the rates differ sevenfold among paralogs, indicating that very different selective forces are acting on the genes of the cluster. Mapping of sequence differences onto a model of the tertiary structure of the enzymes indicates that motifs contributing to substrate binding and catalysis have changed radically in the αE4s and suggest that this subgroup of α-esterases may be evolving into a substantially different functional niche.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002390010075
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  • 4
    Electronic Resource
    Electronic Resource
    Duplication and Divergence of the Genes of the α-Esterase Cluster of Drosophila melanogaster (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 241-252 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Esterase — Gene cluster — Pseudogene —Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The α-esterase cluster of D. melanogaster contains 11 esterase genes dispersed over 60 kb. Embedded in the cluster are two unrelated open reading frames that have sequence similarity with genes encoding ubiquitin-conjugating enzyme and tropomyosin. The esterase amino acid sequences show 37–66% identity with one another and all but one have all the motifs characteristic of functional members of the carboxyl/cholinesterase multigene family. The exception has several frameshift mutations and appears to be a pseudogene. Patterns of amino acid differences among cluster members in relation to generic models of carboxyl/cholinesterase protein structure are broadly similar to those among other carboxyl/cholinesterases sequenced to date. However the α-esterases differ from most other members of the family in: their lack of a signal peptide; the lack of conservation in cysteines involved in disulfide bridges; and in four indels, two of which occur in or adjacent to regions that align with proposed substrate-binding sites of other carboxyl/cholinesterases. Phylogenetic analyses clearly identify three simple gene duplication events within the cluster. The most recent event involved the pseudogene which is located in an intron of another esterase gene. However, relative rate tests suggest that the pseudogene remained functional after the duplication event and has become inactive relatively recently. The distribution of indels also suggests a deeper node in the gene phylogeny that separates six genes at the two ends of the cluster from a block of five in the middle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006083
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  • 5
    Electronic Resource
    Electronic Resource
    Duplication and divergence of the genes of the α-esterase cluster ofDrosophila melanogaster (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 241-252 
    Details
    ISSN: 1432-1432
    Keywords: Esterase ; Gene cluster ; Pseudogene ; Drosophila melanogaster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The α-esterase cluster ofD. melanogaster contains 11 esterase genes dispersed over 60 kb. Embedded in the cluster are two unrelated open reading frames that have sequence similarity with genes encoding ubiquitin-conjugating enzyme and tropomyosin. The esterase amino acid sequences show 37–66% identity with one another and all but one have all the motifs characteristic of functional members of the carboxyl/cholinesterase multigene family. The exception has several frameshift mutations and appears to be a pseudogene. Patterns of amino acid differences among cluster members in relation to generic models of carboxyl/cholinesterase protein structure are broadly similar to those among other carboxyl/cholinesterases sequenced to date. However the α-esterases differ from most other members of the family in: their lack of a signal peptide; the lack of conservation in cysteines involved in disulfide bridges; and in four indels, two of which occur in or adjacent to regions that align with proposed substrate-binding sites of other carboxyl/cholinesterases. Phylogenetic analyses clearly identify three simple gene duplication events within the cluster. The most recent event involved the pseudogene which is located in an intron of another esterase gene. However, relative rate tests suggest that the pseudogene remained functional after the duplication event and has become inactive relatively recently. The distribution of indels also suggests a deeper node in the gene phylogeny that separates six genes at the two ends of the cluster from a block of five in the middle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02338832
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular analysis of thelethal(1)B214 region at the base of theX chromosome ofDrosophila melanogaster (1992)
    Springer
    Chromosoma 101 (1992), S. 456-466 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Approximately 50 kb of genomic DNA was isolated from polytene chromosome bands 19F1 and 2 ofDrosophila melanogaster. Bands 19F1 and 2 are in the immediate vicinity of the β-heterochromatin at the base of theX chromosome and encompass thelittle flylike andlethal(1)B214 complementation groups. The cloned DNA consists of an approximately 21 kb stretch of unique or low copy number sequence that is bounded by repetitive elements interspersed with further unique sequences. The presence of repeated sequences is characteristic of regions within and adjacent to β-heterochromatin. At least part of a tRNA gene cluster is present within the 50 kb of cloned DNA. The cloned region also produces at least 18 discrete size classes of developmentally regulated poly(A)+ RNA species. A 2 kb EcoRI fragment (E10), which lies in the 21 kb stretch of unique sequence, generates seven of these transcripts (of sizes 3.5, 3.35, 2.1, 2.0, 1.5, 1.2 and 1.0 kb) in wild-type flies. However, a small deletion of approximately 75 bp in E10 in alethal(1)B214 mutant allele is associated with alterations in the production or processing of all seven of these transcripts. These data identify E10 sequences as belonging to thelethal(1)B214 gene and suggest that the wild-typelethal(1)B214 gene encodes multiple transcripts. Furthermore, no transcripts of the same size and having the same developmental profile as those generated by the wild-type E10 fragment were identified by probes covering the remainder of the cloned region. This suggests that at least the larger transcripts hybridizing to E10 are partly transcribed from sequences located outside the cloned region, which indicates that thelethal(1)B214 gene extends for more than 20 kb and contains other transcriptionally active sequences within it.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582840
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of the EstP Protein in Drosophila melanogaster and Its Conservation in Drosophilids (1997)
    Springer
    Biochemical genetics 35 (1997), S. 251-271 
    Details
    ISSN: 1573-4927
    Keywords: EstP ; EST7 ; gene duplication ; gene regulation ; carboxylesterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The β-esterase cluster of D. melanogaster comprises two tandemly duplicated genes. Est6 encodes the well-characterized 5′ gene, but the product of the second gene, denoted EstP, had not previously been identified. Here we show that the EstP gene encodes the carboxylesterase EST7. Expression of EstP using the Baculovirus system led to production of a carboxylesterase biochemically indistinguishable from EST7. Furthermore, a naturally occurring EstP variant produces greatly reduced amounts of EstP mRNA and no detectable EST7 protein. Finally, introduction of a wild-type copy of EstP by germline transformation into the variant strain confers the wild-type EST7 phenotype. We show that EST7 differs from EST6 in its substrate and inhibitor specificities and tissue distribution. Germline transformation experiments show that EstP expression is controlled by sequences located between 192 bp 5′ and 609 bp 3′ of the EstP coding region. Data comparisons with other drosophilid esterases suggest that the site of expression, and hence the function, of EST7 has been conserved across lineages in both the subgenera Drosophila and Sophophora.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021897016276
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  • 8
    Electronic Resource
    Electronic Resource
    Biochemistry of Esterases Associated with Organophosphate Resistance in Lucilia cuprina with Comparisons to Putative Orthologues in Other Diptera (1997)
    Springer
    Biochemical genetics 35 (1997), S. 17-40 
    Details
    ISSN: 1573-4927
    Keywords: organophosphorus insecticide resistance ; esterase ; Lucilia cuprina ; Musca domestica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Esterase activities associated with organophosphate insecticide resistance in the Australian sheep blowfly, Lucilia cuprina, are compared with similar activities in other Diptera. The enzymes making the major contribution to methyl butyrate hydrolysis (“ali-esterase”) in L. cuprina, M. domestica, and D. melanogaster comigrate during electrophoresis. The enzymes in L. cuprina and D. melanogaster correspond to the naphthyl acetate hydrolyzing E3 and EST23 isozymes of those species. These and previously published data suggest that the ali-esterases of all three species are orthologous. Strains of L. cuprina fall into four groups on the basis of quantitative determinations of their ali-estesterase, OP hydrolase, and malathion carboxylesterase activities and these groups correspond to their status with respect to two types of OP resistance. Strains susceptible to OPs have high ali-esterase, low OP hydrolase, and intermediate MCE activities; those resistant to malathion but not diazinon have low ali-esterase, intermediate OP hydrolase, and high MCE activities; those resistant to diazinon but not malathion have low ali-esterase, high OP hydrolase, and low MCE activities; those resistant to both OPs have low ali-esterase, high OP hydrolase, and high MCE activities. The correlated changes among the three biochemical and two resistance phenotypes suggest that they are all properties of one gene/enzyme system; three major allelic variants of that system explain OP susceptibility and the two types of OP resistance. Models are proposed to explain the joint contribution of OP hydrolase and MCE activities to malathion resistance and the invariant association of low ali-esterase and elevated OP hydrolase activities in either type of resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022256412623
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of the residue adjacent to the reactive serine on the substrate interactions ofDrosophila esterase 6 (1993)
    Springer
    Biochemical genetics 31 (1993), S. 259-278 
    Details
    ISSN: 1573-4927
    Keywords: serine esterase ; substrate interactions ; Drosophila ; acetylcholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Esterase 6 fromDrosophila melanogaster is a carboxylesterase that belongs to the serine esterase multigene family. It has a basic histidine (His) at residue 187, adjacent to the reactive serine (Ser) at residue 188, whereas most other characterized members of the family have an acidic glutamate (Glu) in the equivalent position. We have used site-directedin vitro mutagenesis to replace the His codon of the esterase 6 gene with either Gln or Glu codons. The enzymes encoded by these active-site mutants and a wild-type control have been expressed, purified, and characterized. Substitution of Gln for His at position 187 has little effect on the biochemical properties of esterase 6, but the presence of Glu at this position is associated with three major differences. First, the pH optimum is increased from 7 to 9. Second, the mutant enzyme shows decreased activity for β-naphthyl esters andp-nitrophenyl acetate but has gained the ability to hydrolyze acetylthiocholine. Finally, the Gibb's free energy of activation for the enzyme is increased. These results suggest that residue 187 interacts directly with the substrate alkyl group and that this interaction is fully realized in the transition state. We further propose that the presence of His rather than Glu at position 187 in esterase 6 contributes significantly to its functional divergence from the cholinesterases and that this divergence is due to different interactions between residue 187 and the substrate alkyl group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553170
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  • 10
    Electronic Resource
    Electronic Resource
    A cluster of at least three esterase genes inLucilia cuprina includes malathion carboxylesterase and two other esterases implicated in resistance to organophosphates (1994)
    Springer
    Biochemical genetics 32 (1994), S. 437-453 
    Details
    ISSN: 1573-4927
    Keywords: Lucilia cuprina ; malathion carboxylesterase ; organophosphate resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Three distinct malathion carboxylesterase (MCE) phenotypes have been identified among strains ofLucilia cuprina. The high-activity phenotype shows 1.6-and 33-fold more MCE specific activity than the intermediate- and low-activity phenotypes, respectively. Flies with high MCE activity are 1000-fold more resistant to malathion than flies with either low or intermediate MCE phenotypes, which are equally susceptible. High and low MCE specific activity are allelic and encoded by theRmal gene on chromosome 4.Rmal is clustered within one map unit of two other esterase genes,Rop1 andE9, which are implicated in resistance to other organophosphate insecticides. Intermediate MCE specific activity is also inherited within the cluster, although its allelism toRmal, Rop1, orE9 is unclear. The cluster does not contain the gene for the hemolymph esterase E4, which maps 6.1 map units fromRop1, on the other side of thebubbled wing marker. The cluster appears to be homologous to part of a tandem array of 11 esterase genes on chromosome 3R ofDrosophila melanogaster.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566064
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