scholarly journals Biochemical and thermodynamic characterization of mutated β1,4-galactosyltransferase 7 involved in the progeroid form of the Ehlers–Danlos syndrome

2010 ◽  
Vol 432 (2) ◽  
pp. 303-311 ◽  
Author(s):  
Sophie Rahuel-Clermont ◽  
Franck Daligault ◽  
Marie-Helene Piet ◽  
Sandrine Gulberti ◽  
Patrick Netter ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Ex Vivo ◽  
Soluble Proteins ◽  
Titration Calorimetry ◽  
Wild Type ◽  
Gene Encoding ◽  
Ehlers Danlos Syndrome ◽  
Chain Initiation ◽  
Danlos Syndrome

Three mutations of the B4GALT7 gene [encoding β1,4-GalT7 (β1,4-galactosyltransferase 7)], corresponding to A186D, L206P and R270C, have been identified in patients with the progeroid form of the Ehlers–Danlos syndrome and are described as being associated with the reduction or loss of β1,4-GalT7 activity. However, the molecular basis of the reduction or loss of activity remained to be determined. In the present study, wild-type, A186D, L206P and R270C β1,4-GalT7 were expressed in CHO618 cells as membrane proteins and in Escherichia coli as soluble proteins fused to MBP (maltose-binding protein). The ability of the expressed proteins to transfer galactose from donor to acceptor substrates was systematically characterized by kinetic analysis. The physicochemical properties of soluble proteins were explored by isothermal titration calorimetry, which is a method of choice when determining the thermodynamic parameters of the binding of substrates. Together, the results showed that: (i) the L206P mutation abolished the activity when L206P β1,4GalT7 was either inserted in the membrane or expressed as a soluble MBP–full-length fusion protein; (ii) the A186D mutation weakly impaired the binding of the donor substrate; and (iii) the R270C mutation strongly impaired the binding of the acceptor substrate. Moreover, the ex vivo consequences of the mutations were investigated by evaluating the priming efficiency of xylosides on GAG (glycosaminoglycan) chain initiation. The results demonstrate a quantitative effect on GAG biosynthesis, depending on the mutation; GAG biosynthesis was fully inhibited by the L206P mutation and decreased by the R270C mutation, whereas the A186D mutation did not affect GAG biosynthesis severely.

Molecular characterization of three mutations in katG affecting the activity of hydroperoxidase I of Escherichia coli

1990 ◽  
Vol 68 (7-8) ◽  
pp. 1037-1044 ◽  
Author(s):  
Peter C. Loewen ◽  
Jacek Switala ◽  
Mark Smolenski ◽  
Barbara L. Triggs-Raine
Keyword(s):  
Escherichia Coli ◽  
Specific Activity ◽  
Polymerase Chain Reaction Amplification ◽  
Protein A ◽  
Wild Type ◽  
Wild Type Enzyme ◽  
Gene Encoding ◽  
Reaction Amplification ◽  
Mutant Genes

Hydroperoxidase I (HPI) of Escherichia coli is a bifunctional enzyme exhibiting both catalase and peroxidase activities. Mutants lacking appreciable HPI have been generated using nitrosoguanidine and the gene encoding HPI, katG, has been cloned from three of these mutants using either classical probing methods or polymerase chain reaction amplification. The mutant genes were sequenced and the changes from wild-type sequence identified. Two mutants contained G to A changes in the coding strand, resulting in glycine to aspartate changes at residues 119 (katG15) and 314 (katG16) in the deduced amino acid sequence of the protein. A third mutant contained a C to T change resulting in a leucine to phenylalanine change at residue 139 (katG14). The Phe139-, Asp119-, and Asp314-containing mutants exhibited 13, < 1, and 18%, respectively, of the wild-type catalase specific activity and 43, 4, and 45% of the wild-type peroxidase specific activity. All mutant enzymes bound less protoheme IX than the wild-type enzyme. The sensitivities of the mutant enzymes to the inhibitors hydroxylamine, azide, and cyanide and the activators imidazole and Tris were similar to those of the wild-type enzyme. The mutant enzymes were more sensitive to high temperature and to β-mercaptoethanol than the wild-type enzyme. The pH profiles of the mutant catalases were unchanged from the wild-type enzyme.Key words: catalase, hydroperoxidase I, mutants, sequence analysis.

Characterization of yeast V-ATPase mutants lacking Vph1p or Stv1p and the effect on endocytosis

2002 ◽  
Vol 205 (9) ◽  
pp. 1209-1219 ◽  
Author(s):  
Natalie Perzov ◽  
Vered Padler-Karavani ◽  
Hannah Nelson ◽  
Nathan Nelson
Keyword(s):  
Sucrose Gradient ◽  
Ph Sensor ◽  
Wild Type ◽  
Gene Encoding ◽  
Yeast Saccharomyces Cerevisiae ◽  
Vacuolar Acidification ◽  
Atpase Subunits ◽  
Immunological Assays ◽  
Gradient Fractionation

SUMMARYSubunit a of V-ATPase in the yeast Saccharomyces cerevisiae, in contrast to its other subunits, is encoded by two genes VPH1 and STV1. While disruption of any other gene encoding the V-ATPase subunits results in growth arrest at pH 7.5, null mutants of Vph1p or Stv1p can grow at this pH. We used a polyclonal antibody to yeast Stv1p and a commercially available monoclonal antibody to Vph1p for analysis of yeast membranes by sucrose gradient fractionation, and two different vital dyes to characterize the phenotype of vph1 ▵ and stv1 ▵mutants as compared to the double mutant and the wild-type cells. Immunological assays of sucrose gradient fractions revealed that the amount of Stv1p was elevated in the vph1 ▵ strain, and that vacuoles purified by this method with no detectable endosomal contamination contain an assembled V-ATPase complex, but with much lower activity than the wild type. These results suggest that Stv1p compensates for the loss of Vph1p in the vph1 ▵ strain. LysoSensor Green DND-189 was used as a pH sensor to demonstrate unexpected changes in vacuolar acidification in stv1▵ as the Vph1p-containing V-ATPase complex is commonly considered to acidify the vacuoles. In the vph1 ▵ strain, the dye revealed slight but definite acidification of the vacuole as well. The lipophilic dye FM4-64 was used as an endocytic marker. We show that the null V-ATPase mutants, as well as the vph1 ▵ one, markedly slow down endocytosis of the dye.

Renal and cardiovascular characterization of COX-2 knockdown mice

2009 ◽  
Vol 296 (6) ◽  
pp. R1751-R1760 ◽  
Author(s):  
Francesca Seta ◽  
Andrew D. Chung ◽  
Patricia V. Turner ◽  
Jeffrey D. Mewburn ◽  
Ying Yu ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Ductus Arteriosus ◽  
Site Mutation ◽  
Gene Encoding ◽  
Developmental Problems ◽  
Cerebrovascular Events ◽  
Complete Disruption ◽  
Cox 2 ◽  
Cox 2 Inhibitors

Selective cyclooxygenase-2 (COX-2) inhibitors (coxibs) increase the incidence of cardiovascular and cerebrovascular events. Complete disruption of the murine gene encoding COX-2 ( Ptgs2) leads to renal developmental problems, as well as female reproductive anomalies and patent ductus arteriosus of variable penetrance in newborns, thus rendering this genetic approach difficult to compare with coxib administration. Here, we created hypomorphic Ptgs2 (COX-2Neo/Neo) mice in which COX-2 expression is suppressed to an extent similar to that achieved with coxibs, but not eliminated, in an attempt to circumvent these difficulties. In LPS-challenged macrophages and cytokine-stimulated endothelial cells obtained from COX-2Neo/Neo mice, COX-2 expression was reduced 70–90%, and these mice developed a mild renal phenotype compared with COX-2 mice possessing an active site mutation (COX-2Y385F/Y385F), with minimal signs of renal dysfunction as measured by FITC-inulin clearance and blood urea nitrogen. These COX-2 knockdown mice displayed an increased propensity for thrombogenesis compared with their wild-type (COX-2+/+) littermates observed by intravital microscopy in cremaster muscle arterioles upon ferric chloride challenge. Measurement of urinary prostanoid metabolites indicated that COX-2Neo/Neo mice produced 50% less prostacyclin but similar levels of PGE2 and thromboxane compared with COX-2+/+ mice in the absence of any blood pressure and ex vivo platelet aggregation abnormalities. COX-2Neo/Neo mice, therefore, provide a genetic surrogate of coxib therapy with disrupted prostacyclin biosynthesis that predisposes to induced arterial thrombosis.

Cytogenetic and array-CGH characterization of a 6q27 deletion in a patient with developmental delay and features of Ehlers-Danlos syndrome

2010 ◽  
Vol 152A (5) ◽  
pp. 1314-1317 ◽  
Author(s):  
A.L. Mosca ◽  
P. Callier ◽  
A. Masurel-Paulet ◽  
C. Thauvin-Robinet ◽  
N. Marle ◽  
...  
Keyword(s):  
Developmental Delay ◽  
Array Cgh ◽  
Ehlers Danlos Syndrome ◽  
Danlos Syndrome

Ex vivo nonlinear microscopy imaging of Ehlers–Danlos syndrome-affected skin

2018 ◽  
Vol 310 (5) ◽  
pp. 463-473 ◽  
Author(s):  
Norbert Kiss ◽  
Dóra Haluszka ◽  
Kende Lőrincz ◽  
Enikő Kuroli ◽  
Judit Hársing ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Nonlinear Microscopy ◽  
Microscopy Imaging ◽  
Ehlers Danlos Syndrome ◽  
Danlos Syndrome

Characterization of mutant alleles of myospheroid, the gene encoding the beta subunit of the Drosophila PS integrins.

Genetics ◽  
1992 ◽  
Vol 132 (2) ◽  
pp. 519-528 ◽  
Author(s):  
T A Bunch ◽  
R Salatino ◽  
M C Engelsgjerd ◽  
L Mukai ◽  
R F West ◽  
...  
Keyword(s):  
Chromosome Pairing ◽  
Protein Product ◽  
Beta Subunit ◽  
Wild Type ◽  
Muscle Attachment ◽  
Negative Interaction ◽  
Gene Encoding ◽  
Attachment Sites ◽  
Muscle Attachment Sites

Abstract This paper presents the characterization of nine alleles of myospheroid, which encodes the beta PS subunit of the Drosophila PS integrins. On Southern blots, the mysXB87, mysXN101 and mysXR04 genes yield restriction digest patterns similar to that seen for wild-type chromosomes, however the mys1 and mysXG43 genes contain detectable deletions. mys1, mysXB87 and mysXG43 make little or no stable protein product, and genetically behave as strong lethal alleles. For the mysXN101 mutation, protein product is seen on immunoblots and a reduced amount of beta PS protein is seen at muscle attachment sites of embryos; this mutant protein retains some wild-type function, as revealed by complementation tests with weak alleles. Protein is also seen on immunoblots from mysXR04 embryos, and this allele behaves as an antimorph, being more deleterious in some crosses than the complete deficiency for the locus. mysts2 and mysnj42 are typically lethal in various combinations with other alleles at high temperatures only, but even at high physiological temperatures, neither appears to eliminate gene function completely. The complementation behaviors of mysts1 and mysts3 are quite unusual and suggest that these mutations involve regulatory phenomena. For mysts3, the data are most easily explained by postulating transvection effects at the locus. The results for mysts1 are less straightforward, but point to the possibility of a chromosome pairing-dependent negative interaction.

scholarly journals Characterization of a Gene Encoding an Acetylase Required for Pyoverdine Synthesis in Pseudomonas aeruginosa

2006 ◽  
Vol 188 (8) ◽  
pp. 3149-3152 ◽  
Author(s):  
Iain L. Lamont ◽  
Lois W. Martin ◽  
Talia Sims ◽  
Amy Scott ◽  
Mary Wallace
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Molecular Basis ◽  
Type Ii ◽  
Gene Encoding ◽  
Different Strains ◽  
Pyoverdine Synthesis

ABSTRACT Strains of Pseudomonas aeruginosa secrete one of three pyoverdine siderophores (types I to III). We have characterized a gene, pvdY II (for the pvdY gene present in type II P. aeruginosa strains), that is only present in strains that make type II pyoverdine. A mutation in pvdY II prevented pyoverdine synthesis. Bioinformatic, genetic, and biochemical approaches indicate that the PvdYII enzyme catalyzes acetylation of hydroxyornithine. Expression of pvdY II is repressed by the presence of iron and upregulated by the presence of type II pyoverdine. Characterization of pvdY II provides insights into the molecular basis for production of different pyoverdines by different strains of P. aeruginosa.

scholarly journals Identification and Characterization of the Bacillus thuringiensis phaZ Gene, Encoding New Intracellular Poly-3-Hydroxybutyrate Depolymerase

2006 ◽  
Vol 188 (21) ◽  
pp. 7592-7599 ◽  
Author(s):  
Chi-Ling Tseng ◽  
Hui-Ju Chen ◽  
Gwo-Chyuan Shaw
Keyword(s):  
Bacillus Thuringiensis ◽  
Wild Type ◽  
Gene Encoding ◽  
Significant Similarity ◽  
Phb Depolymerase ◽  
New Type ◽  
Identification And Characterization

ABSTRACTA gene that codes for a novel intracellular poly-3-hydroxybutyrate (PHB) depolymerase has now been identified in the genome ofBacillus thuringiensissubsp.israelensisATCC 35646. This gene, previously annotated as a hypothetical 3-oxoadipate enol-lactonase (PcaD) gene and now designatedphaZ, encodes a protein that shows no significant similarity with any known PHB depolymerase. Purified His-tagged PhaZ could efficiently degrade trypsin-activated native PHB granules as well as artificial amorphous PHB granules and release 3-hydroxybutyrate monomer as a hydrolytic product, but it could not hydrolyze denatured semicrystalline PHB. In contrast, purified His-tagged PcaD ofPseudomonas putidawas unable to degrade trypsin-activated native PHB granules and artificial amorphous PHB granules. TheB. thuringiensisPhaZ was inactive againstp-nitrophenylpalmitate, tributyrin, and triolein. Sonication supernatants of the wild-typeB. thuringiensiscells exhibited a PHB-hydrolyzing activity in vitro, whereas those prepared from aphaZmutant lost this activity. ThephaZmutant showed a higher PHB content than the wild type at late stationary phase of growth in a nutrient-rich medium, indicating that this PhaZ can function as a PHB depolymerase in vivo. PhaZ contains a lipase box-like sequence (G-W-S102-M-G) but lacks a signal peptide. A purified His-tagged S102A variant had lost the PHB-hydrolyzing activity. Taken together, these results indicate thatB. thuringiensisharbors a new type of intracellular PHB depolymerase.

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