AN ANALYSIS OF XANTHINE DEHYDROGENASE NEGATIVE MUTANTS OF THE ROSY LOCUS IN DROSOPHILA MELANOGASTER

1979 ◽  
Vol 21 (3) ◽  
pp. 379-389 ◽  
Author(s):  
Lois E. Girton ◽  
Reggie Y. C. Lo ◽  
John B. Bell
Keyword(s):  
Drosophila Melanogaster ◽  
Xanthine Dehydrogenase ◽  
Cross Reactivity ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Intragenic Complementation

Eighteen alleles of the rosy locus in Drosophila melanogaster were characterized to identify putative nonsense mutants. Seven alleles exhibited no evidence of intragenic complementation, no evidence of immunological cross-reactivity to antibodies elicited by wild type xanthine dehydrogenase (XDH), and of course were completely deficient in measurable XDH activity. It is possible that one or more of these highly negative ry alleles are nonsense mutants. The remaining eleven ry alleles code for XDH molecules that retain some antigenic similarities to the wild type enzyme as assessed by immunoelectrophoresis and six of these eleven were capable of intragenic complementation.

scholarly journals INTRACISTRONIC MAPPING OF ELECTROPHORETIC SITES IN DROSOPHILA MELANOGASTER: FIDELITY OF INFORMATION TRANSFER BY GENE CONVERSION

Genetics ◽  
1974 ◽  
Vol 76 (2) ◽  
pp. 289-299
Author(s):  
Margaret McCarron ◽  
William Gelbart ◽  
Arthur Chovnick
Keyword(s):  
Drosophila Melanogaster ◽  
Information Transfer ◽  
Large Scale ◽  
Genetic Basis ◽  
Xanthine Dehydrogenase ◽  
Specific Protein ◽  
Wild Type ◽  
Electrophoretic Variation ◽  
The Stability ◽  
Recombination Experiments

ABSTRACT A convenient method is described for the intracistronic mapping of genetic sites responsible for electrophoretic variation of a specific protein in Drosophila melanogaster. A number of wild-type isoalleles of the rosy locus have been isolated which are associated with the production of electrophoretically distinguishable xanthine dehydrogenases. Large-scale recombination experiments were carried out involving null enzyme mutants induced on electrophoretically distinct wild-type isoalleles, the genetic basis for which is followed as a nonselective marker in the cross. Additionally, a large-scale recombination experiment was carried out involving null enzyme rosy mutants induced on the same wild-type isoallele. Examination of the electrophoretic character of crossover and convertant products recovered from the latter experiment revealed that all exhibited the same parental electrophoretic character. In addition to documenting the stability of the xanthine dehydrogenase electrophoretic character, this observation argues against a special mutagenesis hypothesis to explain conversions resulting from allele recombination studies.

scholarly journals Evidence that cysteine-166 is the active-site nucleophile of Pseudomonas aeruginosa amidase: crystallization and preliminary X-ray diffraction analysis of the enzyme

1999 ◽  
Vol 340 (3) ◽  
pp. 711-714 ◽  
Author(s):  
Sebastien FARNAUD ◽  
Renée TATA ◽  
Maninder K. SOHI ◽  
Tommy WAN ◽  
Paul R. BROWN ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Diffraction Analysis ◽  
Active Site ◽  
Quaternary Structure ◽  
Cross Reactivity ◽  
Polyclonal Antiserum ◽  
Wild Type ◽  
X Ray Diffraction ◽  
Wild Type Enzyme ◽  
X Ray

Wild-type and site-specific mutants C166S and C166A (Cys-166 → Ser and Cys-166 → Ala respectively) of the amidase (acylamide amidohydrolase, EC 3.5.1.4) from Pseudomonas aeruginosa were expressed in Escherichia coli by using the vector pKK223-3. Both mutant proteins were catalytically inactive but showed complete cross-reactivity with polyclonal antiserum raised against the wild-type enzyme, as well as CD spectra identical with that of the wild-type enzyme, which were indicative of correct folding. Cys-166 is therefore implicated as the active-site nucleophile. Titration of free thiol groups with 5,5ʹ-dithiobis-(2-nitrobenzoic acid) indicated that Cys-166 is not a rapidly reacting residue. Crystals of both wild-type and C166S amidase grew with identical, rhombohedral morphology; X-ray diffraction analysis established the unit cell dimensions (a = b = c = 84 Å; α = β = γ = 75 °) and space group (R3 or R32). These results imply a quaternary structure of six subunits, with most probably 32 symmetry; the existence of a hexameric structure was supported by molecular mass determinations based on gel filtration and electrophoretic mobility.

Complementation at the Maroon-like Eye-Color Locus of Drosophila melanogaster

Science ◽  
1960 ◽  
Vol 131 (3416) ◽  
pp. 1810-1811 ◽  
Author(s):  
Edward Glassman ◽  
William Pinkerton
Keyword(s):  
Drosophila Melanogaster ◽  
Xanthine Dehydrogenase ◽  
Wild Type ◽  
Eye Color ◽  
Enzyme Substrates

Two "allelic" Drosophila melanogaster mutants which are deficient in xanthine dehydrogenase can complement one another in heterozygotes. This complementation is due to the production of small amounts of xanthine dehydrogenase, enough of which is present to restore the normal eye color. However, not enough of the enzyme is present to produce normal amounts of the enzyme products, or to reduce the accumulation of the enzyme substrates to levels found in wild-type flies.

THE CONTROL OF ALDEHYDE OXIDASE AND XANTHINE DEHYDROGENASE ACTIVITIES AND CRM LEVELS BY THE mal LOCUS IN DROSOPHILA MELANOGASTER

1982 ◽  
Vol 24 (1) ◽  
pp. 11-17 ◽  
Author(s):  
M. M. Bentley ◽  
J. H. Williamson
Keyword(s):  
Drosophila Melanogaster ◽  
Full Advantage ◽  
Aldehyde Oxidase ◽  
Xanthine Dehydrogenase ◽  
Complementation Group ◽  
Activity Levels ◽  
Wild Type ◽  
Eye Color ◽  
Pleiotropic Phenotype

The effects of five new mal alleles on aldehyde oxidase (AO) and xanthine dehydrogenase (XDH) activities and CRM levels in Drosophila melanogaster are described. These alleles were isolated by taking full advantage of the pleiotropic phenotype exhibited by all previously described mal alleles and represent at least three unique examples of mal function. At least one of these alleles is a representative of a new complementation group. Two other alleles exhibit a wild-type eye color in homozygous stock and one of these is "leaky", exhibiting some 50% of the XDH activity normally found in Oregon-R control flies and some 12% of the AO activity. CRM and activity levels have been quantitated for both enzymes in all allelic heterozygotes. XDH-CRM levels vary only slightly around wild-type levels while AO-CRM levels appear much more sensitive to mutational alterations.

THE CONTROL OF ALDEHYDE OXIDASE AND XANTHINE DEHYDROGENASE ACTIVITIES BY THE CINNAMON GENE IN DROSOPHILA MELANOGASTER

1979 ◽  
Vol 21 (4) ◽  
pp. 457-471 ◽  
Author(s):  
Michael M. Bentley ◽  
John H. Williamson
Keyword(s):  
Drosophila Melanogaster ◽  
Aldehyde Oxidase ◽  
Heat Stability ◽  
Xanthine Dehydrogenase ◽  
Wild Type ◽  
Eye Color ◽  
Isolation And Characterization ◽  
Heat Labile ◽  
Complementation Groups

The isolation and characterization of 16 alleles of the cinnamon (cin, 1-0.0) locus in Drosophila melanogaster are described. The effects of cin on viability and the maternal effect of cin+ on eye color have been separated from each other as well as from the deficiency for aldehyde oxidase (AO) and xanthine dehydrogenase (XDH) activities. These 16 alleles have been assigned to four complementation groups based on analysis of AO and XDH activities in all heteroallelic female combinations. Zygotic complementation for lethality and eye color has been characterized and allows the ordering of cin alleles in a consistent pattern for the ability to produce viable zygotes and/or complement for the eye color phene. Several complementing cin combinations were analyzed for heat stability of AO. In all cases, AO from allelic heterozygotes was more heat labile than wild-type AO. One cin allele, cin13, produces heat labile AO in combination with cin+ from Oregon-R, hence exhibiting a "dominant" heat stability phenotype.

scholarly journals Disulfide bond engineering of AppA phytase for increased thermostability requires co-expression of protein disulfide isomerase in Pichia pastoris

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Laura Navone ◽  
Thomas Vogl ◽  
Pawarisa Luangthongkam ◽  
Jo-Anne Blinco ◽  
Carlos H. Luna-Flores ◽  
...  
Keyword(s):  
Pichia Pastoris ◽  
Phytic Acid ◽  
Disulfide Bond ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
E Coli ◽  
Biochemical Characterisation ◽  
Disulfide Bond Isomerase ◽  
Microbial Systems ◽  
Protein Disulfide

Abstract Background Phytases are widely used commercially as dietary supplements for swine and poultry to increase the digestibility of phytic acid. Enzyme development has focused on increasing thermostability to withstand the high temperatures during industrial steam pelleting. Increasing thermostability often reduces activity at gut temperatures and there remains a demand for improved phyases for a growing market. Results In this work, we present a thermostable variant of the E. coli AppA phytase, ApV1, that contains an extra non-consecutive disulfide bond. Detailed biochemical characterisation of ApV1 showed similar activity to the wild type, with no statistical differences in kcat and KM for phytic acid or in the pH and temperature activity optima. Yet, it retained approximately 50% activity after incubations for 20 min at 65, 75 and 85 °C compared to almost full inactivation of the wild-type enzyme. Production of ApV1 in Pichia pastoris (Komagataella phaffi) was much lower than the wild-type enzyme due to the presence of the extra non-consecutive disulfide bond. Production bottlenecks were explored using bidirectional promoters for co-expression of folding chaperones. Co-expression of protein disulfide bond isomerase (Pdi) increased production of ApV1 by ~ 12-fold compared to expression without this folding catalyst and restored yields to similar levels seen with the wild-type enzyme. Conclusions Overall, the results show that protein engineering for enhanced enzymatic properties like thermostability may result in folding complexity and decreased production in microbial systems. Hence parallel development of improved production strains is imperative to achieve the desirable levels of recombinant protein for industrial processes.

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