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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ethylene-induced abscission in leaf and fruit explants of peach involves different enzymes. In leaves abscission is accompanied by increased occurrence of cellulase forms differing in isoelectric point (pI 6.5 and 9.5). A polypeptide with a molecular mass of 51 kDa gives in a western blot a strong cross-reaction with an antibody raised against a maturation cellulase from avocado fruit. Cellulase activity is also found in abscising fruit explants but the amount is very low compared to that of the leaf explants. A northern analysis with a cellulase clone from avocado reveals the presence of two hybridizing mRNAs with a size of 2.2 kb and 1.8 kb, respectively. The steady-state level of the 2.2 kb mRNA is significantly increased by treatment with ethylene. Polygalacturonases are not detected in abscising leaves, but are strongly induced by ethylene in fruit explants. Of the three forms found, two are exopolygalacturonases while the third is an endoenzyme. Ethylene activates preferentially the endoenzyme and the basic exoenzyme but depresses the acid exopolygalacturonases. A northern analysis carried out with a cDNA coding for tomato endopolygalacturonase shows hybridization only with one endopolygalacturonase mRNA form in the fruit abscission zone. Treatment with ethylene causes an increase in the steady-state level of this mRNA. The differences in the enzyme patterns observed in fruit and leaf abscission zones and a differential enzyme induction suggest the feasibility to regulate fruit abscission in peach with the aid of antisense RNA genes.
Plant Mol Biol 1992 Dec
PMID:Cellulase and polygalacturonase involvement in the abscission of leaf and fruit explants of peach. 128 37

Streptomyces reticuli produces an unusual cellulase (Avicelase), with an apparent molecular weight of 82 kDa, which is solely sufficient to degrade crystalline cellulose. During cultivation the processing of the Avicelase to a truncated enzyme (42 kDa) and an inactive protein (40 kDa) correlated with the occurrence of an extracellular protease. After its purification this 36 kDa protease cleaved the S. reticuli Avicelase in vitro in the same manner. Using antibodies raised against the Avicelase and its truncated form (42 kDa) and gene libraries of S. reticuli DNA in the Escherichia coli phage vectors lambda gt11 and Charon 35, the Avicelase gene (cel1) was identified. Further subcloning and DNA-sequencing revealed a G+C rich (72%) reading frame of 2238 bp encoding a protein of 746 amino acids. The transcriptional start site was mapped about 180 bp upstream from the GTG start codon. A signal sequence of 29 amino acids was identified by aligning the deduced amino acids with the characterized N-terminus of the 82 kDa Avicelase. Comparison of the N-terminal amino acids from the purified proteins with the amino acid sequence derived from the Avicelase gene revealed that the truncated enzyme (42 kDa) corresponds to the C-terminal region whereas the inactive proteolytically derived protein (40 kDa) represents the N-terminal part of the 82 kDa Avicelase. Comparisons with amino acid sequences deduced from known cellulase genes indicated the presence of three putative protein domains: (i) an N-terminal part showing significant similarity with a repeat region of endoglucanase C from Cellulomonas fimi, recently shown to be a cellulose-binding domain; (ii) an adjoining region sharing homology with the N-terminal domains with unknown function of endoglucanase A from Pseudomonas fluorescens, endoglucanase D from Clostridium thermocellum and a cellodextrinase from Butyrivibrio fibrisolvens, and (iii) a C-terminal catalytic domain belonging to cellulase family E.
Mol Microbiol 1992 Dec
PMID:The gene encoding the cellulase (Avicelase) Cel1 from Streptomyces reticuli and analysis of protein domains. 128 94

A cDNA (xynA), encoding xylanase A (XYLA), was isolated from a cDNA library, derived from mRNA extracted from the rumen anaerobic fungus, Neocallimastix patriciarum. Recombinant XYLA, purified from Escherichia coli harbouring xynA, had a M(r) of 53,000 and hydrolysed oat-spelt xylan to xylobiose and xylose. The enzyme did not hydrolyse any cellulosic substrates. The nucleotide sequence of xynA revealed a single open reading frame of 1821 bp coding for a protein of M(r) 66,192. The predicted primary structure of XYLA comprised an N-terminal signal peptide followed by a 225-amino-acid repeated sequence, which was separated from a tandem 40-residue C-terminal repeat by a threonine/proline linker sequence. The large N-terminal reiterated regions consisted of distinct catalytic domains which displayed similar substrate specificities to the full-length enzyme. The reiterated structure of XYLA suggests that the enzyme was derived from an ancestral gene which underwent two discrete duplications. Sequence comparison analysis revealed significant homology between XYLA and bacterial xylanases belonging to cellulase/xylanase family G. One of these homologous enzymes is derived from the rumen bacterium Ruminococcus flavefaciens. The homology observed between XYLA and a rumen prokaryote xylanase could be a consequence of the horizontal transfer of genes between rumen prokaryotes and lower eukaryotes, either when the organisms were resident in the rumen, or prior to their colonization of the ruminant. It should also be noted that Neocallimastix XYLA is the first example of a xylanase which consists of reiterated sequences. It remains to be established whether this is a common phenomenon in other rumen fungal plant cell wall hydrolases.
Mol Microbiol 1992 Aug
PMID:Homologous catalytic domains in a rumen fungal xylanase: evidence for gene duplication and prokaryotic origin. 140 48

An electrophoretic karyotype has been established for Trichoderma reesei strain QM6a, and several of its derivatives, by pulsed-field gel electrophoresis. All strains examined appear to have seven chromosomes with a total genome size of approximately 33 megabases (Mb). The sizes of the chromosomal bands in strain QM6a are approximately 6.2, 6.0, 5.1, 4.2 (doublet), 3.6 and 3.2 Mb. Genes encoding the cellulase complex and xylanases of T. reesei have been mapped, as have several other genes.
Mol Microbiol 1992 Aug
PMID:Chromosomal and genetic analysis of the electrophoretic karyotype of Trichoderma reesei: mapping of the cellulase and xylanase genes. 140 56

We have used a targeted gene deletion event to remove the coding region for the bgl1 gene encoding an extracellular beta-glucosidase from the genome of the cellulolytic fungus Trichoderma reesei. The bgl1 null mutants were used to investigate the role of beta-glucosidase in the hydrolysis of cellulose and induction of the other cellulolytic enzyme components. In the absence of extracellular beta-glucosidase, growth of bgl1 null strains on several carbon sources was the same as that of the parent (as measured by mycelial dry weight). However, levels of extracellular protein and total endoglucanase production were seen to lag relative to those levels observed in the control strain. The mRNA levels of the CBHI, CBHII, EGI, and EGII cellulase genes (cbh1, cbh2, egl1 and egl3) showed a corresponding lag in induction, suggesting that the absence of extracellular beta-glucosidase has an effect on the co-ordinate regulation of the other cellulase genes at the level of transcription. The addition of a potent inducer of the cellulase complex (sophorose) resulted in normal rates of cellulase gene mRNA production and extracellular protein release. This indicates that the absence of beta-glucosidase is not affecting some intrinsic cellular ability to produce mRNA or secrete protein. These data suggest that a functional beta-glucosidase is at least partially responsible for the efficient induction of the depolymerase enzymes of the cellulase complex. The observation that the cellulase complex is induced, albeit after a lag, suggests that other enzymes are present that can substitute for the function of beta-glucosidase during induction.
Mol Microbiol 1992 Nov
PMID:The bgl1 gene encoding extracellular beta-glucosidase from Trichoderma reesei is required for rapid induction of the cellulase complex. 145 60

In vitro gene fusions were constructed between the polygalacturonase-encoding pehA gene of the Erwinia carotovora subsp. carotovora (Ecc) strain SCC3193 and the bla gene of pBR322. The gene fusions obtained (75-2, 75-5 and 75-6) encoded hybrid proteins with the entire signal peptide and 70, 260 or 327 amino acids (aa) of the mature 376 aa PehA protein, respectively, fused to the mature part of the periplasmic beta-lactamase. All three hybrid proteins remained cell-bound in Ecc. High-level expression of the longer fusions 75-5 and 75-6 in Ecc led to reduced growth and viability of the cells. This phenotype was utilized to select for spontaneous extragenic mutations restoring normal cell growth. Two classes of regulatory mutants were obtained by this selection. First, mutants impaired in the production of several exoenzymes, including polygalacturonase, were found. These were phenotypically similar to the previously characterized Exp- mutants. Secondly, mutants specifically impaired in the production of polygalacturonase (designated PehR-), but producing and secreting wild-type levels of pectate lyase and cellulase, were obtained. The PehR- mutations were shown to affect transcriptional activation of the pehA gene. Furthermore, the PehR- as well as PehA- mutants exhibited a reduced virulence phenotype suggesting that polygalacturonase is a virulence factor in Ecc.
Mol Gen Genet 1992 Jul
PMID:Expression of pehA-bla gene fusions in Erwinia carotovora subsp. carotovora and isolation of regulatory mutants affecting polygalacturonase production. 149 88

The nucleotide sequence of engD, an endo-beta-1,4-glucanase gene from Clostridium cellulovorans was determined (Genbank Accession No. M37434). The COOH-terminal part of the gene product, EngD, contained a Thr-Thr-Pro repeated sequence followed by a region that has homology to the exoglucanase of Cellulomonas fimi. EngD and EngB, another C. cellulovorans endoglucanase, show 75% amino acid sequence homology at their NH2-termini, in contrast to their carboxyterminal domains which show no homology. EngD had endoglucanase activity on carboxymethylcellulose (CMC), cellobiosidase activity on p-nitrophenyl-cellobioside (p-NPC), and partial hydrolytic activity on crystalline cellulose (Avicel), while EngB showed hydrolytic activity against only CMC. Chimeric proteins between EngB and EngD were constructed by exchanging the non-homologous COOH-terminal regions. Chimeric proteins that contained the NH2-terminus of EngD retained cellobiosidase activity but chimeras with the EngB NH2-terminus showed no cellobiosidase activity. Hydrolysis of crystalline cellulose (Avicelase activity) was observed only with the enzyme containing the EngD NH2-terminus and EngD COOH-terminus.
Mol Gen Genet 1992 Feb
PMID:Analysis of functional domains of endoglucanases from Clostridium cellulovorans by gene cloning, nucleotide sequencing and chimeric protein construction. 153

Protoplasts were prepared from barley aleurone layers using 'Onozuka' cellulase digestion and purification through a Percoll gradient. Protoplasts prepared by this procedure had a viability ranging from 60% to 80% during the first two days of culture. They were responsive to gibberellic acid (GA) as measured by the stimulation of alpha-amylase synthesis. The GA stimulation was counteracted by abscisic acid (ABA). In the presence of polyethylene glycol (PEG), the protoplasts took up exogenously added plasmid DNA containing the reporter gene coding for chloramphenicol acetyl transferase (CAT) linked to a 35S promoter from cauliflower mosaic virus (CaMV) or to barley alpha-amylase gene promoters and expressed CAT activity. Therefore, barley aleurone layer protoplasts are suitable for analysis of hormone-responsive elements in hydrolase genes.
Plant Mol Biol 1991 Mar
PMID:Barley aleurone layer cell protoplasts as a transient expression system. 183 76

A cellulase gene (endA) was isolated from a library of Ruminococcus flavefaciens strain 17 DNA fragments inserted in pUC13. The endA product showed activity against acid-swollen cellulose, carboxymethyl-cellulose, lichenan, cellopentaose and cellotetraose, but showed no activity against cellotriose or binding to avicel. Nucleotide sequencing indicated an encoded product of 455 amino acids which showed significant sequence similarity (ranging from 56% to 61%) with three endoglucanases from Ruminococcus albus, and with Clostridium thermocellum endoglucanase E. Little relatedness was found with a cellodextrinase previously isolated from R. flavefaciens FD1.
Mol Gen Genet 1991 Aug
PMID:Sequence of a cellulase gene from the rumen anaerobe Ruminococcus flavefaciens 17. 188 16

The cenC gene of Cellulomonas fimi, encoding endoglucanase CenC, has an open reading frame of 1101 codons closely followed by a 9 bp inverted repeat. The predicted amino acid sequence of mature CenC, which is 1069 amino acids long, is very unusual in that it has a 150-amino-acid tandem repeat at the N-terminus and an unrelated 100-amino-acid tandem repeat at the C-terminus. CenC belongs to subfamily E1 of the beta-1,4-glycanases. High-level expression in Escherichia coli of cenC from a 3.6 kbp fragment of C. fimi DNA leads to levels of CenC which exceed 10% of total cell protein. Most of the CenC is in the cytoplasm in an inactive form. About 60% of the active fraction of CenC is in the periplasm. The catalytic properties of the active CenC are indistinguishable from those of native CenC from C. fimi. The Mr of CenC from E. coli and C. fimi is approximately 130 kDa. E. coli and C. fimi also produce an endoglucanase, CenC', of approximate Mr 120kDa and with the same N-terminal amino acid sequence and catalytic properties as CenC. CenC' appears to be a proteolytic product of CenC. CenC and CenC' can bind to cellulose and to Sephadex. CenC is the most active component of the C. fimi cellulase system isolated to date.
Mol Microbiol 1991 May
PMID:Nucleotide sequence of the endoglucanase C gene (cenC) of Cellulomonas fimi, its high-level expression in Escherichia coli, and characterization of its products. 195 99


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