Browsing by Author "Eyzaguirre, J"

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    Acetyl xylan esterase II from Penicillium purpurogenum is similar to an esterase from Trichoderma ressei but lacks a cellulose binding domain
    (1998) Gutiérrez, R; Cederlund, E; Hjelmqvist, L; Peirano, A; Herrera, F; Ghosh, D; Duax, W; Jörnvall, H; Eyzaguirre, J
    Penicillium purpurogenum produces at least two acetyl xylan esterases (AXE I and LI). The AXE II cDNA, genomic DNA and mature protein sequences were determined and show that the axe 2 gene contains two introns, that the primary translation product has a signal peptide of 27 residues, and that the mature protein has 207 residues, The sequence is similar to the catalytic domain of AXE I from Trichoderma reesei (67% residue identity) and putative active site residues are conserved, but the Penicillium enzyme lacks the linker and cellulose binding domain, thus explaining why it does not bind cellulose in contrast to the Tricoderma enzyme. These results point to a possible common ancestor gene for the active site domain, while the linker and the binding domain may have been added to the Trichoderma esterase by gene fusion. (C) 1998 Federation of European Biochemical Societies.
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    Acetyl xylan esterase II from Penicillium purpurogenum is similar to an esterase from Trichoderma ressei but lacks a cellulose binding domain
    (1998) Gutierrez, R; Cederlund, E; Hjelmqvist, L; Peirano, A; Herrera, F; Ghosh, D; Duax, W; Jornvall, H; Eyzaguirre, J
    Penicillium purpurogenum produces at least two acetyl xylan esterases (AXE I and LI). The AXE II cDNA, genomic DNA and mature protein sequences were determined and show that the axe 2 gene contains two introns, that the primary translation product has a signal peptide of 27 residues, and that the mature protein has 207 residues, The sequence is similar to the catalytic domain of AXE I from Trichoderma reesei (67% residue identity) and putative active site residues are conserved, but the Penicillium enzyme lacks the linker and cellulose binding domain, thus explaining why it does not bind cellulose in contrast to the Tricoderma enzyme. These results point to a possible common ancestor gene for the active site domain, while the linker and the binding domain may have been added to the Trichoderma esterase by gene fusion. (C) 1998 Federation of European Biochemical Societies.
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    An α-L-arabinofuranosidase from Penicillium purpurogenum
    (2000) De Ioannes, P; Peirano, A; Steiner, J; Eyzaguirre, J
    Penicillium purpurogenum secretes arabinofuranosidase to the growth medium. Highest levels of enzyme (1.0 U ml(-1)) are obtained when L-arabitol is used as carbon source, while 0.85 and 0.7 U ml(-1) are produced with sugar beet pulp and oat spelts xylan, respectively. By means of a zymogram, three bands with arabinofuranosidase activity have been detected in the supernatant of a culture grown in oat spelts xylan. One of the enzymes was purified to homogeneity from this supernatant using gel filtration (BioGel P-100), cation exchange chromatography (CM-Sephadex C-50), hydrophobic interaction chromatography (phenyl agarose) and a second BioGel P-100 column. The enzyme is a monomer of 58 kDa with a pI of 6.5. Optimum pH is 4.0 and optimal temperature 50 degrees C. The arabinofuranosidase is highly specific for alpha-L-arabinofuranosides and liberates arabinose from arabinoxylan. The enzyme shows hyperbolic kinetics towards p-nitrophenyl-alpha-L-arabinofuranoside with a K-M of 1.23 mM. A 36-residue N-terminal sequence is over 70% identical to that of fungal arabinofuranosidases belonging to family 54 of the glycosyl hydrolases. Based on the sequence similarity and other biochemical properties it is proposed that the purified enzyme from P. purpurogenum belongs to family 54. (C) 2000 Elsevier Science B.V. All rights reserved.
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    Cloning, sequencing and expression of the cDNA of endoxylanase B from Penicillium purpurogenum
    (1997) Diaz, R; Sapag, A; Peirano, A; Steiner, J; Eyzaguirre, J
    The cDNA, for xylanase B from Penicillium purpurogenum was cloned and sequenced. This DNA encodes a protein of 208 amino acids which is expected to yield a protein of 183 residues upon processing of the N terminus. The sequence of the predicted protein is very similar to that of 40 other xylanase domains which belong to family G of cellulases/xylanases (73-21% identity).
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    Determination of a protein structure by iodination
    (1999) Ghosh, D; Erman, M; Sawicki, M; Lala, P; Weeks, DR; Li, NY; Pangborn, W; Thiel, DJ; Jörnvall, H; Gutierrez, R; Eyzaguirre, J
    Enzymatic and non-enzymatic iodination of the amino acid tyrosine is a well known phenomenon. The iodination technique has been widely used for labeling proteins, Using high-resolution X-ray crystallographic techniques, the chemical and three-dimensional structures of iodotyrosines formed by non-enzymatic incorporation of I atoms into tyrosine residues of a crystalline protein are described. Acetylxylan esterase (AXE II; 207 amino-acid residues) from Penicillium purpurogenum has substrate specificities towards acetate esters of D-xylopyranose residues in xylan and belongs to a new class of alpha/beta hydrolases. The crystals of the enzyme are highly ordered, tightly packed and diffract to better than sub-angstrom resolution at 85 K. The iodination technique has been utilized to prepare an isomorphous derivative of the AXE II crystal. The structure of the enzyme determined at 1.10 Angstrom resolution exclusively by normal and anomalous scattering from I atoms, along with the structure of the iodinated complex at 1.80 Angstrom resolution, demonstrate the formation of covalent bonds between I atoms and C atoms at ortho positions to the hydroxyl groups of two tyrosyl moieties, yielding iodotyrosines.
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    Differences in expression of two endoxylanase genes (xynA and xynB) from Penicillium purpurogenum
    (2002) Chávez, R; Schachter, K; Navarro, C; Peirano, A; Aguirre, C; Bull, P; Eyzaguirre, J
    A number of xylanolytic microorganisms secrete to the medium several molecular forms of endoxylanases. The physiological function of these isoforms is not clears one possibility is that they are produced under different growth conditions. To study this problem, we have used two endoxylanases (XynA and XynB) produced by the fungus Penicillium purpurogenum. These enzymes have been previously purified and characterized; they belong to family 10 and 11 of the glycosyl hydrolases, respectively. The promoters of the xynA and xynB genes have been sequenced: both present consensus sequences for the binding of the carbon catabolite repressor CreA, but otherwise show substantial differences. The xynB promoter has eight boxes in tandem for the binding of the XlnR activator and lacks the consensus sequence for the PacC pH regulator. On the other hand, the xynA promoter contains one XlnR box and three PacC consensus sequences. To investigate if these differences are reflected in gene expression, Northern blot assays were carried out. The xynA gene is transiently expressed when oat spell xylan is used as carbon source, but negligible expression was observed with birchwood xylan, xylose or xylitol. In contrast, xynB is broadly induced by all these carbon sources; this may be related to the presence of several XlnR boxes. Similar results were obtained by zymogram analysis of the expressed proteins. The different induction capabilities of birchwood and oat spelt xylan may be due to differences in their composition and structure. Expression assays carried out at different pH reflects that, despite the lack of PacC binding sites in the xynB promoter, this gene is tightly regulated by pH. The findings described here illustrate new and important differences between endoxylanases from families 10 and 11 in P. purpurogenum. They may help explain the production of multiple endoxylanase forms by this organism. (C) 2002 Published by Elsevier Science B.V.
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    Electrophoretic karyotype of the filamentous fungus Penicillium purpurogenum and chromosomal location of several xylanolytic genes
    (2001) Chávez, R; Fierro, F; Gordillo, F; Martín, JF; Eyzaguirre, J
    The electrophoretic karyotype of the filamentous fungus Penicillium purpurogenum has been resolved. Using contour-clamped homogeneous electric field gel electrophoresis, five chromosomal bands were separated, with estimated sizes of 7.1, 5.2, 3.7, 2.9 and 2.3 Mbp, giving a total genome size of 21.2 Mbp. To our knowledge, this is the smallest Penicillium genome determined so far. By Southern blots and using homologous probes, the chromosomal location of five xylanolytic genes from P. purpurogenum was determined: axel (acetyl xylan esterase I), xynB (endoxylanase B) and abf1 (arabinofuranosidase 1) in chromosome I, xynA (endoxylanase A) in chromosome II, and axeII (acetyl xylan esterase II) in chromosome Ill. This is the first study where the location of xylanase genes in a Penicillium genome has been established. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
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    Multiple conformations of catalytic serine and histidine in acetylxylan esterase at 0.90 Å
    (2001) Ghosh, D; Sawicki, M; Lala, P; Erman, M; Pangborn, W; Eyzaguirre, J; Gutiérrez, R; Jörnvall, H; Thiel, DJ
    Acetylxylan esterase (AXEII; 207 amino acids) from Penicillium purpurogenum has substrate specificities toward acetate esters of D-xylopyranose residues in xylan and belongs to a new class of alpha/beta hydrolases. The crystal structure of AXEII has been determined by single isomorphous replacement and anomalous scattering, and refined at 0.90- and 1.10-Angstrom resolutions with data collected at 85 K and 295 K, respectively. The tertiary structure consists of a doubly wound alpha/beta sandwich, having a central six-stranded parallel beta -sheet flanked by two parallel ol-helices on each side. The catalytic residues Ser(90), His(187), and Ap(175) are located at the C-terminal end of the sheet, an exposed region of the molecule. The serine and histidine side chains in the 295 K structure show the frequently observed conformations in which Ser(90) is trans and the hydroxyl group is in the plane of the imidazole ring of His(187), However, the structure at 85 K displays an additional conformation in which Ser(90) side-chain hydroxyl is away from the plane of the imidazole ring of His(187). The His(187) side chain forms a hydrogen bond with a sulfate ion and adopts an altered conformation. The only other known hydrolase that has a similar tertiary structure is Fusarium solani cutinase, The exposed nature of the catalytic triad suggests that AXEII is a pure esterase, i.e. an alpha/beta hydrolase with specificity for nonlipidic polar substrates.
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    Secretion of endoxylanase A from Penicillium purpurogenum by Saccharomyces cerevisiae transformed with genomic fungal DNA
    (2002) Chávez, R; Navarro, C; Calderón, I; Peirano, A; Bull, P; Eyzaguirre, J
    Saccharomyces cerevisiae was transformed with a genomic library from Penicillium purpurogenum, and an endoxylanase-producing yeast clone (named 44A) that grows on xylose or xylan as sole carbon source was isolated. This yeast synthesizes xynA mRNA and secretes endoxylanase A to culture media when grown on xylan or xylose, but not glucose. Analysis by pulse-field gel electrophoresis and sequencing indicates that xynA, including its eight introns, has been inserted into the yeast genome. It was shown by sequencing that clone 44A is able to correctly splice xynA introns. This is the first successful attempt to express a fungal endoxylanase gene in yeast with correct intron splicing. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
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    Short communication
    (1998) Steiner, J; Carmona, P; Ponce, C; Berti, M; Eyzaguirre, J
    Penicillium purpurogenum was mutated with u.v. light to increase xylanase production. The best mutant, UV-64, was treated with N-methyl-N'-nitro-N-nitrosoguanidine and a second generation of mutants was obtained (NG-188 and NG-737). NG-737 produced 125 U of xylanase/ml when grown on oat spelts xylan supplemented with wheat bran compared with 69 U/ml for the wild-type strain. The mutants also showed a 2.2-fold increase in beta-xylosidase as compared with the wild-type.
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    Structure analysis of the endoxylanase A gene from Penicillium purpurogenum
    (2001) Chávez, R; Almarza, C; Schachter, K; Peirano, A; Bull, P; Eyzaguirre, J
    Penicillium purpurogenum produces several endoxylanases, two of which (XynA and XynB) have been purified and characterized. XynB has been sequenced, and it belongs to glycosyl hydrolase family 11. In this publication we report the structure of the xynA gene, The amino terminal sequence of the protein was determined and this allowed the design of oligonucleotides for use in polymerase chain reactions. Different polymerase chain reaction strategies were used to amplify and sequence the entire cDNA and the gene. The gene has an open reading frame of 1450 base pairs, including 8 introns with an average length of 56 base pairs each. Only one copy of this gene is present in the P. purpurogenum genome as shown by Southern blot. The gene encodes a protein of 329 residues (including the signal peptide), and the calculated molecular mass of the mature protein is 31,668 Da. Immunodetection assays of the expressed gene positively identified it as xynA, and sequence alignments indicate a high degree of similarity with family 10 endoxylanases. It is concluded that P. purpurogenum produces endoxylanases of family 10 and 11. The complementary action of endoxylanases of both families may be important for an efficient degradation of xylan by the fungus.
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    The acetyl xylan esterase II gene from Penicillium purpurogenum is differentially expressed in several carbon sources, and tightly regulated by pH
    (2004) Chávez, R; Schachter, K; Navarro, C; Peirano, A; Bull, P; Eyzaguirre, J
    The expression of the acetyl xylan esterase II (axell) gene from Penicillium purpurogenum is repressed by glucose and induced by xylan, as well as to a small degree by xylose and xylitol. This gene is expressed at neutral pH, but not tinder alkaline or acidic conditions, in agreement with previous findings for other xylanolytic genes of this organism. This is the first report showing pH regulation of an axe gene.