scholarly journals LAC4 IS THE STRUCTURAL GENE FOR β-GALACTOSIDASE IN KLUYVEROMYCES LACTIS

Genetics ◽  
1981 ◽  
Vol 98 (4) ◽  
pp. 729-745
Author(s):  
R Michael Sheetz ◽  
Robert C Dickson
Keyword(s):  
Thermal Stability ◽  
Structural Gene ◽  
Gel Electrophoresis ◽  
Kluyveromyces Lactis ◽  
Two Dimensional ◽  
Galactosidase Activity ◽  
Wild Type ◽  
Nonsense Suppressor ◽  
Hydrolysis Of ◽  
Thermal Stability Of

ABSTRACT Using genetic and biochemical techniques, we have determined that β-galactosidase in the yeast Kluyveromyces lactis is coded by the LAC4 locus. The following data support this conclusion: (1) mutations in this locus result in levels of β-galactosidase activity 100-fold lower than levels in uninduced wild type and all other lac- mutants; (2) three of five lac4 mutations are suppressible by an unlinked suppressor whose phenotype suggests that it codes for a nonsense suppressor tRNA; (3) a Lac+ revertant, bearing lac4–14 and this unlinked suppressor, has subnormal levels of β-galactosidase activity, and the Km for hydrolysis of o-nitrophenyl-β, D-galactoside and the thermal stability of the enzyme are altered; (4) the level of β-galactosidase activity per cell is directly proportional to the number of copies of LAC4; (5) analysis of cell-free extracts of strains bearing mutations in LAC4 by two-dimensional acryl-amide gel electrophoresis shows that strains bearing lac4–23 and lac4–30 contain an inactive β-galactosidase whose subunit co-electrophoreses with the wild-type subunit, while no subunit or fragment of the subunit is obs0ervable in lac4–8, lac4–14 or lac4–29 mutants; (6) of all lac4 mutants, only those bearing lac4–23 or lac4–30 contain a protein that cross-reacts with anti-β-galactosidase antibody, a finding consistent with the previous result; and (7) β-galactosidase activity in several Lac+ revertants of strains carrying lac4–23 or lac4–30 has greatly decreased thermostability.

Regulation of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (AldDH) in Aspergillus nidulans

1983 ◽  
Vol 217 (1208) ◽  
pp. 243-264 ◽  
Keyword(s):  
Alcohol Dehydrogenase ◽  
Aspergillus Nidulans ◽  
Structural Gene ◽  
Aldehyde Dehydrogenase ◽  
Gel Electrophoresis ◽  
Regulatory Gene ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Wild Type ◽  
Cell Extracts

There is a single major alcohol dehydrogenase (ADH) and a single major aldehyde dehydrogenase (AldDH) in Aspergillus nidulans . Both ADH and AldDH are induced by ethanol and by acetaldehyde and both are subject to carbon catabolite repression. ADH and AldDH are necessary for the utilization of ethanol and of threonine, indicating that both compounds are utilized via acetaldehyde. ADH and AldDH each give a single major activity band on gel electrophoresis. Sodium dodecyl sulphate polyacrylamide gel electrophoresis of cell extracts shows at least two similar ADH polypeptides of approximate relative molecular mass (r. m. m.) 41000 and two similar AldDH polypeptides of approximate r. m. m. 57000. The in vitro translation of mRNA from induced, carbon derepressed wild-type cells gives up to three ADH polypeptides in the r. m. m. range 39000-43000 and an AldDH polypeptide of approximate r. m. m. 57000. The mRNA from uninduced, carbon repressed wild-type cells does not direct the synthesis of the ADH and AldDH polypeptides. This indicates that the regulation of ADH and AldDH is at the level of transcription and/or post-transcriptional modification. The probable explanation of the multiple ADH polypeptides is post-transcriptional modification of the mRNA. Allyl alcohol mutants were made by using diepoxyoctane and γ-rays as mutagens. There are two classes, alcA and alcR . Neither class can utilize ethanol or threonine as a carbon source. The alcA mutants lack normal ADH and are recessive. Of the 47 alcA mutants examined 39 do not make the ADH polypeptides while eight do so. Therefore alcA is the structural gene for ADH. The two alcA mutants tested do not make functional mRNA for ADH. The alcR mutants lack both ADH and AldDH and are recessive. No alcR mutants make the ADH or the AldDH polypeptides. The three alcR mutants tested do not make functional ADH or AldDH mRNA. The mutant alcR 125 is a nonsense mutant, which establishes that alcR codes for a protein. The alcA and alcR genes are adjacent on chromosome VII and a preliminary fine-structure map of the alcA gene has been made. Three mutants that cannot utilize ethanol or threonine and have ADH, but lack AldDH, define a gene AldA on chromosome VIII. The aldA 23 mutant makes the AldDH polypeptides, the other two aldA mutants do not. Therefore aldA is probably the structural gene for AldDH. Our current hypothesis is that alcA and aldA are the structural genes for ADH and AldDH respectively and alcR is a transacting regulatory gene coding for a protein whose function is necessary for the expression of the alcA and aldA genes.

Fabrication and Surface Engineering of Two-Dimensional SnS Toward Piezoelectric Nanogenerator Application

MRS Advances ◽  
2018 ◽  
Vol 3 (45-46) ◽  
pp. 2809-2814 ◽  
Author(s):  
Naoki Higashitarumizu ◽  
Hayami Kawamoto ◽  
Keiji Ueno ◽  
Kosuke Nagashio
Keyword(s):  
Thermal Stability ◽  
Surface Morphology ◽  
Oxide Layer ◽  
Chemical Treatment ◽  
Surface Engineering ◽  
Lone Pair ◽  
Covalent Bonding ◽  
Two Dimensional ◽  
Lone Pair Electrons ◽  
Thermal Stability Of

ABSTRACTMechanical exfoliation is performed to fabricate ultrathin SnS layers, and chemical/thermal stability of SnS layers is discussed in comparison with GeS, toward piezoelectric nanogenerator application. Both SnS and GeS are difficult to be exfoliated under 10 nm using tape exfoliation due to strong interlayer ionic bonding by lone pair electrons in Sn or Ge atoms. Au-mediated exfoliation enables to fabricate larger-scale ultrathin SnS and GeS layers thinner than 10 nm owing to strong semi-covalent bonding between Au and S atoms, but GeS surface immediately degrades during Au etching in an oxidative KI/I2 solution. Although the surface of SnS after the Au-mediated exfoliation reveals several-nm oxide layer of SnOx, the surface morphology retains the flatness unlike the case of GeS. The SnS layers are more robust than GeS against the thermal annealing as well as the chemical treatment, suggesting that SnOx works as a passivation layer for SnS. Self-passivated SnS monolayer can be obtained by a controlled post-oxidation.

scholarly journals Molecular Characterization of Cycloinulooligosaccharide Fructanotransferase from Bacillus macerans

2001 ◽  
Vol 67 (2) ◽  
pp. 995-1000 ◽  
Author(s):  
Hwa-Young Kim ◽  
Yong-Jin Choi
Keyword(s):  
Escherichia Coli ◽  
Thermal Stability ◽  
Striking Difference ◽  
Bacillus Macerans ◽  
Specific Manner ◽  
Specificity Constant ◽  
Processing Event ◽  
Hydrolysis Of ◽  
Thermal Stability Of

ABSTRACT Cycloinulooligosaccharide fructanotransferase (CFTase) converts inulin into cyclooligosaccharides of β-(2→1)-linkedd-fructofuranose by catalyzing an intramolecular transfructosylation reaction. The CFTase gene was cloned and characterized from Bacillus macerans CFC1. The CFTase gene encoded a polypeptide of 1,333 amino acids with a calculatedM r of 149,563. Western blot and zymography analyses revealed that the CFTase with a molecular mass of 150 kDa (CFT150) was processed (between Ser389 and Phe390 residue) to form a 107-kDa protein (CFT107) in the B. macerans CFC1 cells. The processed CFT107 was similar in its mass to the previously purified CFTase from B. macerans CFC1. The CFT107 enzyme was produced by B. macerans CFC1 but was not detected from the recombinant Escherichia coli cells, indicating that the processing event occurred in a host-specific manner. The two CFTases (CFT150 and CFT107) exhibited the same enzymatic properties, such as influences of pH and temperature on the enzyme activity, the intermolecular transfructosylation ability, and the ability of hydrolysis of cycloinulooligosaccharides produced by the cyclization reaction. However, the thermal stability of CFT107 was slightly higher than that of CFT150. The most striking difference between the two enzymes was observed in their Km values; the value for CFT150 (1.56 mM) was threefold lower than that for CFT107 (4.76 mM). Thus, the specificity constant (k cat/Km ) of CFT150 was about fourfold higher than that of CFT107. These results indicated that the N-terminal 358-residue region of CFT150 played a role in increasing the enzyme's binding affinity to the inulin substrate.

scholarly journals MUTATIONS AFFECTING SYNTHESIS OF β-GALACTOSIDASE ACTIVITY IN THE YEAST KLUYVEROMYCES LACTIS

Genetics ◽  
1980 ◽  
Vol 95 (4) ◽  
pp. 877-890
Author(s):  
R Michael Sheetz ◽  
Robert C Dickson
Keyword(s):  
Enzyme Activity ◽  
Kluyveromyces Lactis ◽  
Single Mutation ◽  
Chromosome 2 ◽  
Wild Type Allele ◽  
Galactosidase Activity ◽  
Wild Type ◽  
Fold Level ◽  
Complementation Groups ◽  
Constitutive Synthesis

ABSTRACT Fifty-one mutants of Kluyveromyces lactis that cannot grow on lactose (Lac-) were isolated and characterized. All of the mutations are in nuclear genes, are recessive in their wild-type allele and define seven complementation groups, which we designate lac3 through lac9. Strains bearing mutations in lac3,lac5, lac7, lac8 and lac9 are also unable to grow on galactose (Gal-). Since the Gal- and Lac- phenotype co-segregate, they are probably due to a single mutation. Strains bearing mutations in any of the seven complementation groups grow normally on glucose. However, strains bearing mutations in lac3, lac5 and lac6 do not grow on glucose if lactose is also present in the medium. Likewise, strains bearing mutations in lac3 and lac5 do not grow on glucose in the presence of galactose. Complementation groups lac4 and lac5 are loosely linked and map within a cluster of auxotrophic mutations on a chromosome that we designate Chromosome 2. The remaining five groups are unlinked. Thus, there is no evidence for clustering of Lac genes into an operon-like regulatory unit.—To further characterize the nature of the Lac- phenotype, the basal and inducible level of β-galactosidase activity were measured. All mutants had nearly normal basal enzyme levels, except those in lac4, which had barely detectable levels. Inducible enzyme levels varied from barely detectable levels in mutants bearing lac4 mutations up to four-fold inducible levels in strains bearing mutations in other complementation groups. In all cases, however, induction levels were below the 30-fold level obtained in wild-type cells. Three strains bearing lac5 mutations contain increased enzyme activity in the absence of inducer, indicating constitutive synthesis of β-galactosidase. In summary, these data indicate that several genes are necessary for synthesis of β-galactosidase activity.

Thermal stability of wild type and disulfide bridge containing mutant of poplar plastocyanin

2004 ◽  
Vol 112 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Rita Guzzi ◽  
Laura Andolfi ◽  
Salvatore Cannistraro ◽  
Martin Ph. Verbeet ◽  
Gerard W. Canters ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Disulfide Bridge ◽  
Wild Type ◽  
Thermal Stability Of

Thermal Stability of Si/Si0.85Ge0.15/Si Modulation Doped Double Heterostructures

1989 ◽  
Vol 160 ◽  
Author(s):  
P.J. Wang ◽  
B.S. Meyerson ◽  
P.M. Fahey ◽  
F. LeGoues ◽  
G.J. Scilla ◽  
...  
Keyword(s):  
Thermal Stability ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ultra High Vacuum ◽  
Misfit Dislocations ◽  
Two Dimensional ◽  
Double Heterostructures ◽  
Vapor Deposition Technique ◽  
P Type ◽  
Thermal Stability Of

AbstractThe thermal stability of Si/Si0.85Ge0.15/Si p-type modulation doped double heterostructures grown by the Ultra High Vacuum/ Chemical Vapor Deposition technique has been examined by Hall measurement, transmission electron microscopy, secondary ion mass spectroscopy, and Raman spectroscopy. As deposited heterostructures showed two-dimensional hole gas formation at the abrupt Si/SiGe and SiGe/Si interfaces. Annealing at 800 °C. for 1 hr. caused the diffusion of boron acceptors to the heterointerfaces, degrading the hole mobilities observed in the two dimensional hole gas. Rapid redistribution of boron, causing a loss of the 2 dimensional carrier behavior, was observed after a 900 °C, 0.5 hr. anneal. Neither Ge interdiffusion nor the generation of misfit dislocations were observed in the annealed heterostructures, evincing the defect-free crystal quality of these as-grown strained heteroepitaxial layers. The superior stability of these heterostructures have strong positive implications for Si:Ge heterojunction devices.

A two-dimensional coordination polymer containing a two-dimensional zinc–carboxylate layer constructed from helical chains: poly[(μ4-benzene-1,2-dicarboxylato)zinc(II)]

2012 ◽  
Vol 68 (9) ◽  
pp. m235-m237 ◽  
Author(s):  
Wei-Lu Xiong ◽  
Qing-Yan Liu ◽  
Na Zhang ◽  
Leng Wang
Keyword(s):  
Thermal Stability ◽  
Coordination Polymer ◽  
Title Compound ◽  
Two Dimensional ◽  
Tetrahedral Geometry ◽  
Distorted Tetrahedral Geometry ◽  
Building Unit ◽  
Left And Right ◽  
Thermal Stability Of

The title compound, [Zn(C8H4O4)]n, consists of one ZnIIcation and one benzene-1,2-dicarboxylate dianion (BDC2−) as the building unit. The ZnIIcation is four-coordinated by four carboxylate O atoms from four dianionic BDC2−ligands in a distorted tetrahedral geometry. The ZnIIcations are linked by the BDC2−ligands to generate a structure featuring two-dimensional zinc–carboxylate layers containing left- and right-handed helical chains. The two-dimensional layers are stacked along theadirection. The thermal stability of the title compound has been studied.

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