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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

Clostridium thermocellum produces a highly active cellulase system that consists of a high-M(r) multienzyme complex termed cellulosome. Hydrolytic components of the cellulosome are organized around a large, noncatalytic glycoprotein termed CipA that acts both as a scaffolding component and a cellulose-binding factor. Catalytic subunits of the cellulosome bear conserved, noncatalytic subdomains, termed dockerin domains, which bind to receptor domains of CipA, termed cohesin domains. CipA includes nine cohesin domains, a cellulose-binding domain, and a specialized dockerin domain. Proteins of the cell envelope carrying cohesin domains that specifically bind the dockerin domain of CipA have been identified. These proteins may mediate anchoring of the cellulosomes to the cell surface. Cellulase complexes similar to the cellulosome of C. thermocellum are produced by several cellulolytic clostridia. High-M(r) multienzyme complexes have also been identified in anaerobic rumen fungi. The architecture of the fungal complexes also seems to rely on the interaction of conserved, noncatalytic docking domains with a scaffolding component. However, the sequence of the fungal docking domains bears no resemblance to the clostridial dockerin domains, suggesting that the fungal and clostridial complexes arose independently.
Crit Rev Biochem Mol Biol 1996 Jun
PMID:The cellulosome: an exocellular, multiprotein complex specialized in cellulose degradation. 881 76

Cellulase and xylanase cDNAs were isolated from a cDNA library of the polycentric anaerobic fungus Orpinomyces sp. strain PC-2 constructed in Escherichia coli. The cellulase cDNA (celB) was 1.8 kb long with an open reading frame (ORF) coding for a polypeptide of 471 amino acids, and the xylanase cDNA (xynA) was 1.2 kb long with an ORF encoding a polypeptide of 362 amino acids. Single transcripts of 1.9 kb for celB and 1.5 kb for xynA were detected in total RNA of Orpinomyces grown on Avicel. Genomic DNA regions coding for CelA and XynA were devoid of introns. The enzymes were highly homologous (80 to 85% identity) to the corresponding enzymes of the monocentric anaerobic fungus Neocallimastix patriciarum and, like those, contained in addition to a catalytic domain, a noncatalytic repeated peptide domain (NCRPD). The Orpinomyces xylanase contained one catalytic domain and thus differed from the Neocallimastix xylanase, which had two similar catalytic domains (H. J. Gilbert, G. P. Hazlewood, J. I. Lauie, C. G. Orpin, and G. P. Xue, Mol. Microbiol. 6:2065-2072, 1992). Two peptides corresponding to the catalytic domain and the NCRPD of XynA were synthesized, and antibodies against them were raised and affinity column purified. The antibodies against the catalytic domain peptide reacted specifically with the xylanases of Orpinomyces and Neocallimastix, while the antibodies against the NCRPD reacted with many (at least eight) extracellular proteins of Orpinomyces and Neocallimastix, suggesting that the NCRPD is present in a number of polypeptides.
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PMID:Monocentric and polycentric anaerobic fungi produce structurally related cellulases and xylanases. 902 40

Selective ruminants, which prefer easily digestible plants, cannot digest fibrous forage as well as grass eaters. Low enzyme activity or short retention time of ingesta particles in fermentation chambers appeared to be responsible for reduced cellulose breakdown. Seasonal activity of cellulolytic enzymes, cellulose concentration and protozoa population in reticulorumen (RR) and caecocolon (CC) of roe deer as a typical concentrate selector were investigated. Cellulase activities were lowest in winter when cellulose concentration in RR contents were highest. Highest enzyme activities and lowest cellulose concentration were measured in early spring. Cellulolytic activities were significantly correlated with the number of protozoa in RR. Only one entodinomorphic genus was identified in the RR. The enzyme activities in CC were far lower compared with those in RR. Low cellulose digestion in the RR cannot be compensated for by cellulose breakdown in the CC. The reduced cellulose digestion of roe deer may be attributed to the short retention time of food particles in spring and summer, whereas decreased colonisation of microorganisms in the rumen may be the main reason for low cellulose breakdown in winter.
Comp Biochem Physiol A Mol Integr Physiol 1998 Apr
PMID:Activity of cellulolytic enzymes in the contents of reticulorumen and caecocolon of roe deer (Capreolus capreolus). 977 85

Cellulase genes of Pseudotrichonympha grassii (Hypermastigida: Eucomonymphidae), the symbiotic flagellate in the hindgut of the wood-feeding termite Coptotermes formosanus, were isolated and characterized. The nucleotide sequences of the major cellulase component in the hindgut of C. formosanus were determined based on its N-terminal amino acid sequence. The five isolated nucleotide sequences (PgCBH-homos) had an open reading frame of 1350 bp showing similarity to catalytic domains of glycoside hydrolase family (GHF) 7 members, and primary structure comparison with GHF7 members whose tertiary structures are well-characterized revealed the overall similarity between PgCBH-homo and the catalytic domain of a processive cellulase Cel7A (formerly CBHI) from the aerobic fungus Trichoderma reesei. Functional expression of PgCBH-homos in Escherichia coli, using the carboxymethylcellulose-Congo red assay, demonstrated the actual cellulolytic activity of PgCBH-homo. RT-PCR showed that PgCBH-homos were expressed, from the three flagellates in the hindgut, specifically in P. grassii.
Cell Mol Life Sci 2002 Sep
PMID:Cellulase genes from the parabasalian symbiont Pseudotrichonympha grassii in the hindgut of the wood-feeding termite Coptotermes formosanus. 1244 Jul 75

The family Passifloraceae contains many species exploited in the food, pharmaceutical, and ornamental plant industries. The routine culture of isolated protoplasts (naked cells) followed by reproducible plant regeneration, is crucial to the genetic improvement of Passiflora spp. by somatic cell technologies. Such procedures include somatic hybridization by protoplast fusion to generate novel hybrid plants, and gene introduction by transformation. Seedling leaves are a convenient source of totipotent protoplasts. The protoplast-to-plant system developed for Passiflora edulis fv. flavicarpa is summarized in this chapter. The procedure involves enzymatic degradation of leaf tissue using commercially-available Macerozyme R10, Cellulase R10, and Driselase. Isolated protoplasts are cultured in Kao and Michayluk medium, semi-solidified with agarose. The medium containing the suspended protoplasts is dispensed as droplets or thin layers and bathed in liquid medium of the same composition. Shoot regeneration involves transfer of protoplast-derived tissues to Murashige and Skoog-based medium. The protocols developed for P. edulis are applicable to other Passiflora spp. and will underpin the future biotechnological exploitation of a range of species in this important plant family.
Methods Mol Biol 2006
PMID:Isolation, culture, and plant regeneration from leaf protoplasts of Passiflora. 1667 17

The glycosyl hydrolase genes cel5A and xyl3A previously isolated by ourselves within a fragment of DNA from the methagenomic library of cow rumen microflora DNA were sub-cloned and expressed in E. coli. The recombinant proteins Cel5A and Xyl3A were purified and characterized. Cellulase Cel5A belongs to the Family 5 glycosyl hydrolases and is a one-module 38.2 kDa enzyme that hydrolyses the 1,4-glycoside bonds of soluble cellulose substrates and amorphous cellulose, showing its maximal activity (31200 u/mg) on lichenan, a soluble substrate with mixed (beta-1,3-1,4) bonds. The end product of the amorphous cellulose hydrolysis is cellobiose. Cel5A is inactive toward the crystal forms of cellulose. Cel5A is an endoglucanase capable of exohydrolysis. The molecular mass of beta-xylosidase Xyl3A belonging to the Family 3 glycosyl hydrolases is 83.7 kDa. The enzyme is active only on xylooligosaccharides, with the maximal activity shown on xylobiose, the end product of the reaction being xylose. No activity on xylane was hitherto observed. Recombinant Cel5A and Xyl3A are stable over a wide range of pH and temperatures, their maximal activity being observed at pH 6.5 and at 55 degrees C.
Mol Gen Mikrobiol Virusol 2009
PMID:[Expression of the genes CelA and XylA isolated from a fragment of metagenomic DNA in Escherichia coli]. 1951 8

Cellulase enzyme is a key cost component in the production of fuels and chemicals from lignocellulosic biomass. Cellulolytic ability of the enzyme preparation is often measured by activity assays using model substrates such as filter paper. Using lignocellulosic biomass as the substrate to assess enzyme performance has the potential of being more process relevant. We describe two procedures that use washed pretreated cellulosic material to measure the efficacy of cellulase enzymes. First, a saccharification assay that measures glucose yield as a function of the amount of cellulase used in the process. And second, the simultaneous saccharification and fermentation (SSF) assay measures cellulase performance by the amount of ethanol produced from enzymatic hydrolysis of the cellulosic material. You can use both assays to screen cellulases under a variety of substrate types, loadings, and process conditions.
Methods Mol Biol 2009
PMID:Assessing cellulase performance on pretreated lignocellulosic biomass using saccharification and fermentation-based protocols. 1976 26

Reliable, rapid and inexpensive detection of cellulolytic enzymes that can be used for a wide variety of biological and environmental samples are currently in high demand. Here, a new cellulase detection protocol is described that circumvents problems observed with popular agar-based methods by exploiting the ability of carboxymethylcellulose (CMC) to form gel-like surfaces on its own. These pure CMC-layers are sensitive to cellulolytic degradation and stainable by Gram's iodine without showing unwelcome reactions with other enzymes. The staining intensity negatively correlates with the enzyme activity and can be used for quantification. Cellulase activities are not obstructed by high sugar contents (e.g., in plant material) which limit the applicability of other quantification methods, making our new method particularly attractive for screening of plant extracts. A useful variant of this new method is its applicability to plant tissue prints for spatial mapping of the cellulolytic activity in a zymogram-like fashion.
Int J Mol Sci 2014 Jan 09
PMID:Cellulase activity screening using pure carboxymethylcellulose: application to soluble cellulolytic samples and to plant tissue prints. 2441 52

In the heterogeneous semi-solid environment naturally occupied by lignocellulolytic fungi the majority of nutrients are locked away as insoluble plant biomass. Hence, lignocellulolytic fungi must actively search for, and attach to, a desirable source of nutrients. During growth on lignocellulose a period of carbon deprivation provokes carbon catabolite derepression and scavenging hydrolase secretion. Subsequently, starvation and/or contact sensing was hypothesized to play a role in lignocellulose attachment and degradation. In Aspergillus nidulans the extracellular signalling mucin, MsbA, influences growth under nutrient-poor conditions including lignocellulose. Cellulase secretion and activity was affected by MsbA via a mechanism that was independent of cellulase transcription. MsbA modulated both the cell wall integrity and filamentous growth MAPK pathways influencing adhesion, biofilm formation and secretion. The constitutive activation of MsbA subsequently enhanced cellulase activity by increasing the secretion of the cellobiohydrolase, CbhA, while improved substrate attachment and may contribute to an enhanced starvation response. Starvation and/or contact sensing therefore represents a new dimension to the already multifaceted regulation of cellulase activity.
Mol Microbiol 2014 Oct 08
PMID:The Aspergillus nidulans signalling mucin MsbA regulates starvation responses, adhesion and affects cellulase secretion in response to environmental cues. 2529 14


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