Degrassi G

References (6)

Title : Isolation, characterization, and heterologous expression of a carboxylesterase of Pseudomonas aeruginosa PAO1 - Pesaresi_2005_Curr.Microbiol_50_102
Author(s) : Pesaresi A , Devescovi G , Lamba D , Venturi V , Degrassi G
Ref : Curr Microbiol , 50 :102 , 2005
Abstract : We purified to homogeneity an intracellular esterase from the opportunistic pathogen Pseudomonas aeruginosa PAO1. The enzyme hydrolyzes p-nitrophenyl acetate and other acetylated substrates. The N-terminal amino acid sequence was analyzed and 11 residues, SEPLILDAPNA, were determined. The corresponding gene PA3859 was identified in the P. aeruginosa PAO1 genome as the only gene encoding for a protein with this N-terminus. The encoding gene was cloned in Escherichia coli, and the recombinant protein expressed and purified to homogeneity. According to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis and analytical gel filtration chromatography, the esterase was found to be a monomer of approximately 24 kDa. The experimentally determined isoelectric point was 5.2 and the optimal enzyme activity was at 55 degrees C and at pH 9.0. The esterase preferentially hydrolyzed short-chain fatty acids. It is inhibited by phenylmethylsulfonyl fluoride (PMSF) but not by ethylendiaminotetraacetic acid (EDTA). Native enzyme preparations typically showed a Michaelis constant (K(m)) and V(max) of 0.43 mM and 12,500 U mg(-1), respectively, using p-nitrophenyl acetate as substrate. Homology-based database searches clearly revealed the presence of the consensus GXSXG signature motif that is present in the serine-dependent acylhydrolase protein family.
ESTHER : Pesaresi_2005_Curr.Microbiol_50_102
PubMedSearch : Pesaresi_2005_Curr.Microbiol_50_102
PubMedID: 15717224
Gene_locus related to this paper: pseae-PA3859

Title : Heterologous expression, purification, crystallization, X-ray analysis and phasing of the acetyl xylan esterase from Bacillus pumilus - Krastanova_2005_Biochim.Biophys.Acta_1748_222
Author(s) : Krastanova I , Guarnaccia C , Zahariev S , Degrassi G , Lamba D
Ref : Biochimica & Biophysica Acta , 1748 :222 , 2005
Abstract : Bacillus pumilus PS213 acetyl xylan esterase (AXE) acts as an accessory enzyme in the plant cell wall hemicellulose biodegradation pathway. It belongs to the carbohydrate esterase family 7 and hydrolyses the ester linkages of the acetyl groups in position 2 and/or 3 of the xylose moieties of the acetylated xylan fragments from hardwood. The enzyme displays activity towards a broad range of acetylated compounds including the antibiotic cephalosporin-C. In this study we report the heterologous expression, purification, physicochemical characterization and crystallization of the recombinant B. pumilus AXE. Remarkable improvement of the crystal quality was achieved by setting up crystallization conditions, at first established using the hanging drop vapor diffusion method, in a micro-batch experiment. Rod-like diffraction quality crystals were obtained using 10% PEG 6000, 0.1 M MES pH 6.0 and a wide range of LiCl concentrations (0.2-1.0 M) as precipitant agent. Two different crystal forms, both belonging to space group P2(1), were characterized, diffracting X-rays to 2.5 and 1.9 angstrom resolution. Successful molecular replacement showed 12 molecules in the asymmetric unit of either crystal forms that are arranged as two doughnut-like hexamers, each one encompassing a local 32 symmetry. A catalytic inactive mutant Ser181Ala of B. pumilus AXE was also engineered, expressed, purified and crystallized for functional and structural studies.
ESTHER : Krastanova_2005_Biochim.Biophys.Acta_1748_222
PubMedSearch : Krastanova_2005_Biochim.Biophys.Acta_1748_222
PubMedID: 15769599
Gene_locus related to this paper: bacpu-AXE

Title : Purification, crystallization and preliminary X-ray analysis of an acetylxylan esterase from Bacillus pumilus. Erratum - Benini_2004_Acta.Crystallogr.D.Biol.Crystallogr_60_1346
Author(s) : Benini S , Degrassi G , Krastanova I , Lamba D , Venturi V
Ref : Acta Crystallographica D Biol Crystallogr , 60 :1346 , 2004
Abstract : This erratum is to apologise for having reported the crystallization and X-ray characterization of Bacillus pumilus acetylxylan esterase (AXE) while the protein crystallized was instead an inorganic pyrophosphatase, a contaminant of the expression in E. coli. The protein was purified by hydrophobic interaction, ionic exchange and gel filtration, but still contained traces of contaminant proteins. Crystals were obtained in the R32 space group perfectly compatible with the homohexameric structure of AXE. The cell parameters were compatible with a reasonable crystal packing as in the model cephalosporin C deacetylase from Bacillus subtilis kindly provided before publication by Dr Jim Brannigan et al. (PDB code 1ods crystallized in R3 and 1odt crystallized in R32). Since every attempt to solve the structure by molecular replacement using 1odt as a model failed, a search of the PDB using the cell parameters of the data collected revealed a match with Escherichia coli inorganic pyrophosphatase (1ipw). A molecular-replacement solution confirmed that the protein crystallized was indeed E. coli inorganic pyrophosphatase present as a contaminant in the protein preparation used for crystallization. This experience should be kept in mind because proteins used for crystallization should be as pure as possible not only to favour the process itself but also to avoid the crystallization of contaminants.
ESTHER : Benini_2004_Acta.Crystallogr.D.Biol.Crystallogr_60_1346
PubMedSearch : Benini_2004_Acta.Crystallogr.D.Biol.Crystallogr_60_1346
PubMedID: 11717513

Title : The acetyl xylan esterase of Bacillus pumilus belongs to a family of esterases with broad substrate specificity - Degrassi_2000_Microbiology_146 ( Pt 7)_1585
Author(s) : Degrassi G , Kojic M , Ljubijankic G , Venturi V
Ref : Microbiology , 146 ( Pt 7) :1585 , 2000
Abstract : The Bacillus pumilus gene encoding acetyl xylan esterase (axe) was identified and characterized. The axe gene was expressed and the recombinant enzyme produced in Escherichia coli was purified and characterized. The recombinant enzyme displayed similar properties to the acetyl xylan esterase (AXE) purified from B. pumilus. The AXE primary structure was 76% identical to the cephalosporin C deacetylase of B. subtilis, and 40% to two recently identified AXEs from Thermoanaerobacterium and Thermotoga maritima. These four proteins are of similar size and represent a new family of esterases having a broad substrate specificity. The recombinant AXE was demonstrated to have activity on several acetylated substrates, including on cephalosporin C.
ESTHER : Degrassi_2000_Microbiology_146 ( Pt 7)_1585
PubMedSearch : Degrassi_2000_Microbiology_146 ( Pt 7)_1585
PubMedID: 10878123
Gene_locus related to this paper: bacpu-AXE

Title : Purification and properties of an esterase from the yeast Saccharomyces cerevisiae and identification of the encoding gene - Degrassi_1999_Appl.Environ.Microbiol_65_3470
Author(s) : Degrassi G , Uotila L , Klima R , Venturi V
Ref : Applied Environmental Microbiology , 65 :3470 , 1999
Abstract : We purified an intracellular esterase that can function as an S-formylglutathione hydrolase from the yeast Saccharomyces cerevisiae. Its molecular mass was 40 kDa, as determined by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point was 5.0 by isoelectric focusing. The enzyme activity was optimal at 50 degrees C and pH 7.0. The corresponding gene, YJLO68C, was identified by its N-terminal amino acid sequence and is not essential for cell viability. Null mutants have reduced esterase activities and grow slowly in the presence of formaldehyde. This enzyme may be involved in the detoxification of formaldehyde, which can be metabolized to S-formylglutathione by S. cerevisiae.
ESTHER : Degrassi_1999_Appl.Environ.Microbiol_65_3470
PubMedSearch : Degrassi_1999_Appl.Environ.Microbiol_65_3470
PubMedID: 10427036
Gene_locus related to this paper: yeast-yjg8

Title : Purification and characterization of an acetyl xylan esterase from Bacillus pumilus - Degrassi_1998_Appl.Environ.Microbiol_64_789
Author(s) : Degrassi G , Okeke BC , Bruschi CV , Venturi V
Ref : Applied Environmental Microbiology , 64 :789 , 1998
Abstract : Bacillus pumilus PS213 was found to be able to release acetate from acetylated xylan. The enzyme catalyzing this reaction has been purified to homogeneity and characterized. The enzyme was secreted, and its production was induced by corncob powder and xylan. Its molecular mass, as determined by gel filtration, is 190 kDa, while sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a single band of 40 kDa. The isoelectric point was found to be 4.8, and the enzyme activity was optimal at 55 degrees C and pH 8.0. The activity was inhibited by most of the metal ions, while no enhancement was observed. The Michaelis contant (Km) and Vmax for alpha-naphthyl acetate were 1.54 mM and 360 micromol min-1 mg of protein-1, respectively.
ESTHER : Degrassi_1998_Appl.Environ.Microbiol_64_789
PubMedSearch : Degrassi_1998_Appl.Environ.Microbiol_64_789
PubMedID: 10215579
Gene_locus related to this paper: bacpu-AXE