Gtgen3A, a novel plant GH3 β-glucosidase, modulates gentio-oligosaccharide metabolism in Gentiana

2018 ◽  
Vol 475 (7) ◽  
pp. 1309-1322 ◽  
Author(s):  
Hideyuki Takahashi ◽  
Sayaka Kikuchi-Fujisaki ◽  
Chiharu Yoshida ◽  
Hidetoshi Yamada ◽  
Tetsuro Yamashita ◽  
...  

Gentiobiose, a β-1,6-linked glycosyl-disaccharide, accumulates abundantly in Gentianaceae and is involved in aspects of plant development, such as fruits ripening and release of bud dormancy. However, the mechanisms regulating the amount of gentio-oligosaccharide accumulation in plants remain obscure. The present study aimed to identify an enzyme that modulates gentio-oligosaccharide amount in gentian (Gentiana triflora). A protein responsible for gentiobiose hydrolysis, GtGen3A, was identified by partial purification and its peptide sequence analysis. The enzyme had a molecular mass of ∼67 kDa without a secretory signal peptide sequence. Sequence analysis revealed that GtGen3A could be a β-glucosidase member belonging to glycoside hydrolase family 3 (GH3). GtGen3A showed a homology to GH3 β-glucan exohydrolases, ExoI of Hordeum vulgare, and ExgI from Zea mays, which preferentially hydrolyzed β-1,3- and β-1,4-linked oligosaccharides. The purified recombinant GtGen3A (rGtGen3A) produced in Escherichia coli showed optimal reaction at pH 6.5 and 20°C. The rGtGen3A liberated glucose from β-1,2-, β-1,3-, β-1,4-, and β-1,6-linked oligosaccharides, and showed the highest activity toward gentiotriose among the substrates tested. Kinetic analysis also revealed that rGtGen3A preferentially hydrolyzed gentiotriose. Virus-induced gene silencing of Gtgen3A in gentian plantlets resulted in predominant accumulation of gentiotriose rather than gentiobiose. Furthermore, the expression level of Gtgen3A was almost similar to the amount of gentiobiose in field-grown gentians. These findings suggest that the main function of GtGen3A is the hydrolysis of gentiotriose to gentiobiose, and that GtGen3A plays a role in modulating gentiobiose amounts in gentian.

2011 ◽  
Vol 347-353 ◽  
pp. 269-276
Author(s):  
Zhe Sun ◽  
Hong Fu Zhang ◽  
Ming Wang

On account of the spreading problem of resistance gene and off-target effects of functional gene products expressed by bacteria, pMG36e, a plasmid with the erythromycin- resistance (Emr) gene, which could shuttle between Lactobacillus and E. coli, was reconstructed into a non-antibiotic secretory expression vector with the beta-Galactosidase (β-Gal) gene for selection, then linked a secretory signal peptide sequence to the non-antibiotic resistance vector, thus the secretory non-antibiotic resistance vector was constructed. Finally, to test the vector's function, the SO7 gene of Eimeria tenella (E. tenella) was cloned into the vector and expressed successfully. This system may be used as a model to explore the feasibility of vaccine vectors using the β-Gal gene for selection, and collect fundamental data for expressing other homogeneous and heterogeneous functional genes in such a novel vector.


2010 ◽  
Vol 9 (11) ◽  
pp. 1650-1660 ◽  
Author(s):  
Encarnación Dueñas-Santero ◽  
Ana Belén Martín-Cuadrado ◽  
Thierry Fontaine ◽  
Jean-Paul Latgé ◽  
Francisco del Rey ◽  
...  

ABSTRACT In yeast, enzymes with β-glucanase activity are thought to be necessary in morphogenetic events that require controlled hydrolysis of the cell wall. Comparison of the sequence of the Saccharomyces cerevisiae exo-β(1,3)-glucanase Exg1 with the Schizosaccharomyces pombe genome allowed the identification of three genes that were named exg1 + (locus SPBC1105.05), exg2 + (SPAC12B10.11), and exg3 + (SPBC2D10.05). The three proteins have different localizations: Exg1 is secreted to the periplasmic space, Exg2 is a membrane protein, and Exg3 is a cytoplasmic protein. Characterization of the biochemical activity of the proteins indicated that Exg1 and Exg3 are active only against β(1,6)-glucans while no activity was detected for Exg2. Interestingly, Exg1 cleaves the glucans with an endohydrolytic mode of action. exg1 + showed periodic expression during the cell cycle, with a maximum coinciding with the septation process, and its expression was dependent on the transcription factor Sep1. The Exg1 protein localizes to the septum region in a pattern that was different from that of the endo-β(1,3)-glucanase Eng1. Overexpression of Exg2 resulted in an increase in cell wall material at the poles and in the septum, but the putative catalytic activity of the protein was not required for this effect.


2007 ◽  
Vol 407 (2) ◽  
pp. 207-217 ◽  
Author(s):  
Claudia Massa ◽  
Mads H. Clausen ◽  
Jure Stojan ◽  
Doriano Lamba ◽  
Cristiana Campa

We have recently isolated and heterologously expressed BcPeh28A, an endopolygalacturonase from the phytopathogenic Gram-negative bacterium Burkholderia cepacia. Endopolygalacturonases belong to glycoside hydrolase family 28 and are responsible for the hydrolysis of the non-esterified regions of pectins. The mode of action of BcPeh28A on different substrates has been investigated and its enzymatic mechanism elucidated. The hydrolysis of polygalacturonate indicates that BcPeh28A is a non-processive enzyme that releases oligomers with chain lengths ranging from two to eight. By inspection of product progression curves, a kinetic model has been generated and extensively tested. It has been used to derive the kinetic parameters that describe the time course of the formation of six predominant products. Moreover, an investigation of the enzymatic activity on shorter substrates that differ in their overall length and methylation patterns sheds light on the architecture of the BcPeh28A active site. Specifically the tolerance of individual sites towards methylated saccharide units was rationalized on the basis of the hydrolysis of hexagalacturonides with different methylation patterns.


2004 ◽  
Vol 186 (15) ◽  
pp. 4885-4893 ◽  
Author(s):  
Takane Katayama ◽  
Akiko Sakuma ◽  
Takatoshi Kimura ◽  
Yutaka Makimura ◽  
Jun Hiratake ◽  
...  

ABSTRACT A genomic library of Bifidobacterium bifidum constructed in Escherichia coli was screened for the ability to hydrolyze the α-(1→2) linkage of 2′-fucosyllactose, and a gene encoding 1,2-α-l-fucosidase (AfcA) was isolated. The afcA gene was found to comprise 1,959 amino acid residues with a predicted molecular mass of 205 kDa and containing a signal peptide and a membrane anchor at the N and C termini, respectively. A domain responsible for fucosidase activity (the Fuc domain; amino acid residues 577 to 1474) was localized by deletion analysis and then purified as a hexahistidine-tagged protein. The recombinant Fuc domain specifically hydrolyzed the terminal α-(1→2)-fucosidic linkages of various oligosaccharides and a sugar chain of a glycoprotein. The stereochemical course of the hydrolysis of 2′-fucosyllactose was determined to be inversion by using 1H nuclear magnetic resonance. The primary structure of the Fuc domain exhibited no similarity to those of any glycoside hydrolases (GHs) but showed high similarity to those of several hypothetical proteins in a database. Thus, it was revealed that the AfcA protein constitutes a novel inverting GH family (GH family 95).


1993 ◽  
Vol 106 (1) ◽  
pp. 31-43 ◽  
Author(s):  
X.R. Wu ◽  
T.T. Sun

Despite the fact that bladder epithelium has many interesting biological features and is a frequent site of carcinoma formation, relatively little is known about its biochemical differentiation. We have shown recently that a 47 kDa glycoprotein, uroplakin III (UPIII), in conjunction with uroplakins I (27 kDa) and II (15 kDa), forms the asymmetric unit membrane (AUM)--a highly specialized biomembrane characteristic of the apical surface of bladder epithelium. Deglycosylation and cDNA sequencing revealed that UPIII contains up to 20 kDa of N-linked sugars attached to a core protein of 28.9 kDa. The presence of an N-terminal signal peptide sequence and a single transmembrane domain located near the C terminus, plus the N-terminal location of all the potential N-glycosylation sites, points to a type I (N-exo/C-cyto) configuration. Thus the mass of the extracellular domain (20 kDa plus up to 20 kDa of sugar) of UPIII greatly exceeds that of its intracellular domain (5 kDa). Such an asymmetrical mass distribution, a feature shared by the other two major uroplakins, provides a molecular explanation as to why the luminal leaflet of AUM is almost twice as thick as the cytoplasmic one. The fact that of the three major proteins of AUM only UPIII has a significant cytoplasmic domain suggests that this molecule may play an important role in AUM-cytoskeleton interaction in terminally differentiated urothelial cells.


1991 ◽  
Vol 279 (1) ◽  
pp. 223-230 ◽  
Author(s):  
P Palomeque-Messia ◽  
S Englebert ◽  
M Leyh-Bouille ◽  
M Nguyen-Distèche ◽  
C Duez ◽  
...  

The low-Mr penicillin-binding protein (PBP)/DD-transpeptidase of Streptomyces K15 is synthesized in the form of a 291-amino acid-residue precursor possessing a cleavable 29-amino acid-residue signal peptide. Sequence-similarity searches and hydrophobic-cluster analysis show that the Streptomyces K15 enzyme, the Escherichia coli PBPs/DD-carboxy-peptidases 5 and 6, the Bacillus subtilis PBP/DD-carboxypeptidase 5 and the spoIIA product (a putative PBP involved in the sporulation of B. subtilis) are structurally related and form a distinct class A of low-Mr PBPs/DD-peptidases. The distribution of the hydrophobic clusters along the amino acid sequences also shows that the Streptomyces K15 PBP, and by extension the other PBPs of class A, have similarity in the polypeptide folding, with the beta-lactamases of class A, with as reference the Streptomyces albus G and Staphylococcus aureus beta-lactamases of known three-dimensional structure. This comparison allows one to predict most of the secondary structures in the PBPs and the amino acid motifs that define the enzyme active sites.


1994 ◽  
Vol 107 (8) ◽  
pp. 2279-2284 ◽  
Author(s):  
L.M. Coluccio

We have previously purified and characterized two myosin-1 isoforms from rat liver (molecular masses 130 kDa and 110 kDa; L. M. Coluccio and C. Conaty (1993) Cell Motil. Cytoskel. 24, 189–199). Here, we describe the purification and characterization from liver of a third myosin-1 (molecular mass 105 kDa) and determine the number of calmodulin molecules associated with each of these three myosin-1 isoforms. The 105 kDa polypeptide, solubilized from liver homogenates with the addition of ATP, co-sediments with F-actin, co-purifies with calmodulin, and binds calmodulin in the presence of EGTA. Antibodies directed against chicken intestinal brush border myosin-1 cross-react with the 105 kDa polypeptide on immunoblots. Partial peptide sequence analysis indicates that the polypeptide corresponds with an MM1 gamma gene product that represents a myosin-1 isoform cloned from mouse brain (Sherr et al. (1993) J. Cell Biol. 120, 1405–1416). A comparison of calmodulin binding to the now three isolated forms of myosin-1 in liver shows that in solution the 105 kDa and 110 kDa polypeptides bind two molecules of calmodulin each whereas the 130 kDa binds six molecules of calmodulin.


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