Gilbert HJ

References (12)

Title : Complex pectin metabolism by gut bacteria reveals novel catalytic functions - Ndeh_2017_Nature_544_65
Author(s) : Ndeh D , Rogowski A , Cartmell A , Luis AS , Basle A , Gray J , Venditto I , Briggs J , Zhang X , Labourel A , Terrapon N , Buffetto F , Nepogodiev S , Xiao Y , Field RA , Zhu Y , O'Neil MA , Urbanowicz BR , York WS , Davies GJ , Abbott DW , Ralet MC , Martens EC , Henrissat B , Gilbert HJ
Ref : Nature , 544 :65 , 2017
Abstract : The metabolism of carbohydrate polymers drives microbial diversity in the human gut microbiota. It is unclear, however, whether bacterial consortia or single organisms are required to depolymerize highly complex glycans. Here we show that the gut bacterium Bacteroides thetaiotaomicron uses the most structurally complex glycan known: the plant pectic polysaccharide rhamnogalacturonan-II, cleaving all but 1 of its 21 distinct glycosidic linkages. The deconstruction of rhamnogalacturonan-II side chains and backbone are coordinated to overcome steric constraints, and the degradation involves previously undiscovered enzyme families and catalytic activities. The degradation system informs revision of the current structural model of rhamnogalacturonan-II and highlights how individual gut bacteria orchestrate manifold enzymes to metabolize the most challenging glycan in the human diet.
ESTHER : Ndeh_2017_Nature_544_65
PubMedSearch : Ndeh_2017_Nature_544_65
PubMedID: 28329766

Title : Evidence that family 35 carbohydrate binding modules display conserved specificity but divergent function - Montanier_2009_Proc.Natl.Acad.Sci.U.S.A_106_3065
Author(s) : Montanier C , van Bueren AL , Dumon C , Flint JE , Correia MA , Prates JA , Firbank SJ , Lewis RJ , Grondin GG , Ghinet MG , Gloster TM , Herve C , Knox JP , Talbot BG , Turkenburg JP , Kerovuo J , Brzezinski R , Fontes CM , Davies GJ , Boraston AB , Gilbert HJ
Ref : Proc Natl Acad Sci U S A , 106 :3065 , 2009
Abstract : Enzymes that hydrolyze complex carbohydrates play important roles in numerous biological processes that result in the maintenance of marine and terrestrial life. These enzymes often contain noncatalytic carbohydrate binding modules (CBMs) that have important substrate-targeting functions. In general, there is a tight correlation between the ligands recognized by bacterial CBMs and the substrate specificity of the appended catalytic modules. Through high-resolution structural studies, we demonstrate that the architecture of the ligand binding sites of 4 distinct family 35 CBMs (CBM35s), appended to 3 plant cell wall hydrolases and the exo-beta-D-glucosaminidase CsxA, which contributes to the detoxification and metabolism of an antibacterial fungal polysaccharide, is highly conserved and imparts specificity for glucuronic acid and/or Delta4,5-anhydrogalaturonic acid (Delta4,5-GalA). Delta4,5-GalA is released from pectin by the action of pectate lyases and as such acts as a signature molecule for plant cell wall degradation. Thus, the CBM35s appended to the 3 plant cell wall hydrolases, rather than targeting the substrates of the cognate catalytic modules, direct their appended enzymes to regions of the plant that are being actively degraded. Significantly, the CBM35 component of CsxA anchors the enzyme to the bacterial cell wall via its capacity to bind uronic acid sugars. This latter observation reveals an unusual mechanism for bacterial cell wall enzyme attachment. This report shows that the biological role of CBM35s is not dictated solely by their carbohydrate specificities but also by the context of their target ligands.
ESTHER : Montanier_2009_Proc.Natl.Acad.Sci.U.S.A_106_3065
PubMedSearch : Montanier_2009_Proc.Natl.Acad.Sci.U.S.A_106_3065
PubMedID: 19218457
Gene_locus related to this paper: celju-b3pei5

Title : The active site of a carbohydrate esterase displays divergent catalytic and noncatalytic binding functions - Montanier_2009_PLoS.Biol_7_e71
Author(s) : Montanier C , Money VA , Pires VM , Flint JE , Pinheiro BA , Goyal A , Prates JA , Izumi A , Stalbrand H , Morland C , Cartmell A , Kolenova K , Topakas E , Dodson EJ , Bolam DN , Davies GJ , Fontes CM , Gilbert HJ
Ref : PLoS Biol , 7 :e71 , 2009
Abstract : Multifunctional proteins, which play a critical role in many biological processes, have typically evolved through the recruitment of different domains that have the required functional diversity. Thus the different activities displayed by these proteins are mediated by spatially distinct domains, consistent with the specific chemical requirements of each activity. Indeed, current evolutionary theory argues that the colocalization of diverse activities within an enzyme is likely to be a rare event, because it would compromise the existing activity of the protein. In contrast to this view, a potential example of multifunctional recruitment into a single protein domain is provided by CtCel5C-CE2, which contains an N-terminal module that displays cellulase activity and a C-terminal module, CtCE2, which exhibits a noncatalytic cellulose-binding function but also shares sequence identity with the CE2 family of esterases. Here we show that, unlike other CE2 members, the CtCE2 domain displays divergent catalytic esterase and noncatalytic carbohydrate binding functions. Intriguingly, these diverse activities are housed within the same site on the protein. Thus, a critical component of the active site of CtCE2, the catalytic Ser-His dyad, in harness with inserted aromatic residues, confers noncatalytic binding to cellulose whilst the active site of the domain retains its esterase activity. CtCE2 catalyses deacetylation of noncellulosic plant structural polysaccharides to deprotect these substrates for attack by other enzymes. Yet it also acts as a cellulose-binding domain, which promotes the activity of the appended cellulase on recalcitrant substrates. The CE2 family encapsulates the requirement for multiple activities by biocatalysts that attack challenging macromolecular substrates, including the grafting of a second, powerful and discrete noncatalytic binding functionality into the active site of an enzyme. This article provides a rare example of "gene sharing," where the introduction of a second functionality into the active site of an enzyme does not compromise the original activity of the biocatalyst.
ESTHER : Montanier_2009_PLoS.Biol_7_e71
PubMedSearch : Montanier_2009_PLoS.Biol_7_e71
PubMedID: 19338387

Title : Crystal structure of a cellulosomal family 3 carbohydrate esterase from Clostridium thermocellum provides insights into the mechanism of substrate recognition - Correia_2008_J.Mol.Biol_379_64
Author(s) : Correia MA , Prates JA , Bras J , Fontes CM , Newman JA , Lewis RJ , Gilbert HJ , Flint JE
Ref : Journal of Molecular Biology , 379 :64 , 2008
Abstract : The microbial degradation of the plant cell wall is of increasing industrial significance, exemplified by the interest in generating biofuels from plant cell walls. The majority of plant cell-wall polysaccharides are acetylated, and removal of the acetyl groups through the action of carbohydrate esterases greatly increases the efficiency of polysaccharide saccharification. Enzymes in carbohydrate esterase family 3 (CE3) are common in plant cell wall-degrading microorganisms but there is a paucity of structural and biochemical information on these biocatalysts. Clostridium thermocellum contains a single CE3 enzyme, CtCes3, which comprises two highly homologous (97% sequence identity) catalytic modules appended to a C-terminal type I dockerin that targets the esterase into the cellulosome, a large protein complex that catalyses plant cell wall degradation. Here, we report the crystal structure and biochemical properties of the N-terminal catalytic module (CtCes3-1) of CtCes3. The enzyme is a thermostable acetyl-specific esterase that exhibits a strong preference for acetylated xylan. CtCes3-1 displays an alpha/beta hydrolase fold that contains a central five-stranded parallel twisted beta-sheet flanked by six alpha-helices. In addition, the enzyme contains a canonical catalytic triad in which Ser44 is the nucleophile, His208 is the acid-base and Asp205 modulates the basic nature of the histidine. The acetate moiety is accommodated in a hydrophobic pocket and the negative charge of the tetrahedral transition state is stabilized through hydrogen bonds with the backbone N of Ser44 and Gly95 and the side-chain amide of Asn124.
ESTHER : Correia_2008_J.Mol.Biol_379_64
PubMedSearch : Correia_2008_J.Mol.Biol_379_64
PubMedID: 18436237

Title : Insights into plant cell wall degradation from the genome sequence of the soil bacterium Cellvibrio japonicus - DeBoy_2008_J.Bacteriol_190_5455
Author(s) : DeBoy RT , Mongodin EF , Fouts DE , Tailford LE , Khouri H , Emerson JB , Mohamoud Y , Watkins K , Henrissat B , Gilbert HJ , Nelson KE
Ref : Journal of Bacteriology , 190 :5455 , 2008
Abstract : The plant cell wall, which consists of a highly complex array of interconnecting polysaccharides, is the most abundant source of organic carbon in the biosphere. Microorganisms that degrade the plant cell wall synthesize an extensive portfolio of hydrolytic enzymes that display highly complex molecular architectures. To unravel the intricate repertoire of plant cell wall-degrading enzymes synthesized by the saprophytic soil bacterium Cellvibrio japonicus, we sequenced and analyzed its genome, which predicts that the bacterium contains the complete repertoire of enzymes required to degrade plant cell wall and storage polysaccharides. Approximately one-third of these putative proteins (57) are predicted to contain carbohydrate binding modules derived from 13 of the 49 known families. Sequence analysis reveals approximately 130 predicted glycoside hydrolases that target the major structural and storage plant polysaccharides. In common with that of the colonic prokaryote Bacteroides thetaiotaomicron, the genome of C. japonicus is predicted to encode a large number of GH43 enzymes, suggesting that the extensive arabinose decorations appended to pectins and xylans may represent a major nutrient source, not just for intestinal bacteria but also for microorganisms that occupy terrestrial ecosystems. The results presented here predict that C. japonicus possesses an extensive range of glycoside hydrolases, lyases, and esterases. Most importantly, the genome of C. japonicus is remarkably similar to that of the gram-negative marine bacterium, Saccharophagus degradans 2-40(T). Approximately 50% of the predicted C. japonicus plant-degradative apparatus appears to be shared with S. degradans, consistent with the utilization of plant-derived complex carbohydrates as a major substrate by both organisms.
ESTHER : DeBoy_2008_J.Bacteriol_190_5455
PubMedSearch : DeBoy_2008_J.Bacteriol_190_5455
PubMedID: 18556790
Gene_locus related to this paper: celju-b3pei5 , celju-b3pf25 , celju-b3pfb5 , celju-b3pgh5 , celju-b3pgz5 , celju-b3ph03 , celju-b3pi00 , celju-b3pi89 , celju-b3pj26 , celju-b3pju5 , celju-b3pks4 , celju-b3pks5 , celju-b3plp7 , celju-metx , celju-b3phr4 , celju-b3pjj6 , celju-b3pcj5 , celju-b3pcu6 , celju-b3pei0

Title : Complete genome sequence of the complex carbohydrate-degrading marine bacterium, Saccharophagus degradans strain 2-40 T - Weiner_2008_PLoS.Genet_4_e1000087
Author(s) : Weiner RM , Taylor LE, 2nd , Henrissat B , Hauser L , Land M , Coutinho PM , Rancurel C , Saunders EH , Longmire AG , Zhang H , Bayer EA , Gilbert HJ , Larimer F , Zhulin IB , Ekborg NA , Lamed R , Richardson PM , Borovok I , Hutcheson S
Ref : PLoS Genet , 4 :e1000087 , 2008
Abstract : The marine bacterium Saccharophagus degradans strain 2-40 (Sde 2-40) is emerging as a vanguard of a recently discovered group of marine and estuarine bacteria that recycles complex polysaccharides. We report its complete genome sequence, analysis of which identifies an unusually large number of enzymes that degrade >10 complex polysaccharides. Not only is this an extraordinary range of catabolic capability, many of the enzymes exhibit unusual architecture including novel combinations of catalytic and substrate-binding modules. We hypothesize that many of these features are adaptations that facilitate depolymerization of complex polysaccharides in the marine environment. This is the first sequenced genome of a marine bacterium that can degrade plant cell walls, an important component of the carbon cycle that is not well-characterized in the marine environment.
ESTHER : Weiner_2008_PLoS.Genet_4_e1000087
PubMedSearch : Weiner_2008_PLoS.Genet_4_e1000087
PubMedID: 18516288
Gene_locus related to this paper: sacd2-q21f03 , sacd2-q21l72 , sacd2-q21ms2 , sacd2-q21ll5

Title : Multifunctional Xylooligosaccharide\/Cephalosporin C Deacetylase Revealed by the Hexameric Structure of the Bacillus subtilis Enzyme at 1.9A Resolution - Vincent_2003_J.Mol.Biol_330_593
Author(s) : Vincent F , Charnock SJ , Verschueren KH , Turkenburg JP , Scott DJ , Offen WA , Roberts S , Pell G , Gilbert HJ , Davies GJ , Brannigan JA
Ref : Journal of Molecular Biology , 330 :593 , 2003
Abstract : Esterases and deacetylases active on carbohydrate ligands have been classified into 14 families based upon amino acid sequence similarities. Enzymes from carbohydrate esterase family seven (CE-7) are unusual in that they display activity towards both acetylated xylooligosaccharides and the antibiotic, cephalosporin C. The 1.9A structure of the multifunctional CE-7 esterase (hereinafter CAH) from Bacillus subtilis 168 reveals a classical alpha/beta hydrolase fold encased within a 32 hexamer. This is the first example of a hexameric alpha/beta hydrolase and is further evidence of the versatility of this particular fold, which is used in a wide variety of biological contexts. A narrow entrance tunnel leads to the centre of the molecule, where the six active-centre catalytic triads point towards the tunnel interior and thus are sequestered away from cytoplasmic contents. By analogy to self-compartmentalising proteases, the tunnel entrance may function to hinder access of large substrates to the poly-specific active centre. This would explain the observation that the enzyme is active on a variety of small, acetylated molecules. The structure of an active site mutant in complex with the reaction product, acetate, reveals details of the putative oxyanion binding site, and suggests that substrates bind predominantly through non-specific contacts with protein hydrophobic residues. Protein residues involved in catalysis are tethered by interactions with protein excursions from the canonical alpha/beta hydrolase fold. These excursions also mediate quaternary structure maintenance, so it would appear that catalytic competence is only achieved on protein multimerisation. We suggest that the acetyl xylan esterase (EC 3.1.1.72) and cephalosporin C deacetylase (EC 3.1.1.41) enzymes of the CE-7 family represent a single class of proteins with a multifunctional deacetylase activity against a range of small substrates.
ESTHER : Vincent_2003_J.Mol.Biol_330_593
PubMedSearch : Vincent_2003_J.Mol.Biol_330_593
PubMedID: 12842474
Gene_locus related to this paper: bacsu-CAH

Title : A modular cinnamoyl ester hydrolase from the anaerobic fungus Piromyces equi acts synergistically with xylanase and is part of a multiprotein cellulose-binding cellulase-hemicellulase complex - Fillingham_1999_Biochem.J_343 Pt 1_215
Author(s) : Fillingham IJ , Kroon PA , Williamson G , Gilbert HJ , Hazlewood GP
Ref : Biochemical Journal , 343 Pt 1 :215 , 1999
Abstract : A collection of clones, isolated from a Piromyces equi cDNA expression library by immunoscreening with antibodies raised against affinity purified multienzyme fungal cellulase-hemicellulase complex, included one which expressed cinnamoyl ester hydrolase activity. The P. equi cinnamoyl ester hydrolase gene (estA) comprised an open reading frame of 1608 nt encoding a protein (EstA) of 536 amino acids and 55540 Da. EstA was modular in structure and comprised three distinct domains. The N-terminal domain was closely similar to a highly conserved non-catalytic 40-residue docking domain which is prevalent in cellulases and hemicellulases from three species of anaerobic fungi and binds to a putative scaffolding protein during assembly of the fungal cellulase complex. The second domain was also not required for esterase activity and appeared to be an atypically large linker comprising multiple tandem repeats of a 13-residue motif. The C-terminal 270 residues of EstA contained an esterase catalytic domain that exhibited overall homology with a small family of esterases, including acetylxylan esterase D (XYLD) from Pseudomonas fluorescens subsp. cellulosa and acetylxylan esterase from Aspergillus niger. This region also contained several smaller blocks of residues that displayed homology with domains tentatively identified as containing the essential catalytic residues of a larger group of serine hydrolases. A truncated variant of EstA, comprising the catalytic domain alone (EstA'), was expressed in Escherichia coli as a thioredoxin fusion protein and was purified to homogeneity. EstA' was active against synthetic and plant cell-wall-derived substrates, showed a marked preference for cleaving 1-->5 ester linkages between ferulic acid and arabinose in feruloylated arabino-xylo-oligosaccharides and was inhibited by the serine-specific protease inhibitor aminoethylbenzene-sulphonylfluoride. EstA' acted synergistically with xylanase to release more than 60% of the esterified ferulic acid from the arabinoxylan component of plant cell walls. Western analysis confirmed that EstA is produced by P. equi and is a component of the aggregated multienzyme cellulase-hemicellulase complex. Hybrid proteins, harbouring one, two or three iterations of the conserved 40-residue fungal docking domain fused to the reporter protein glutathione S-transferase, were produced. Western blot analysis of immobilized P. equi cellulase-hemicellulase complex demonstrated that each of the hybrid proteins bound to a 97 kDa polypeptide in the extracellular complex.
ESTHER : Fillingham_1999_Biochem.J_343 Pt 1_215
PubMedSearch : Fillingham_1999_Biochem.J_343 Pt 1_215
PubMedID: 10493932
Gene_locus related to this paper: pireq-faeb

Title : An Aspergillus niger esterase (ferulic acid esterase III) and a recombinant Pseudomonas fluorescens subsp. cellulosa esterase (Xy1D) release a 5-5' ferulic dehydrodimer (diferulic acid) from barley and wheat cell walls - Bartolome_1997_Appl.Environ.Microbiol_63_208
Author(s) : Bartolome B , Faulds CB , Kroon PA , Waldron K , Gilbert HJ , Hazlewood G , Williamson G
Ref : Applied Environmental Microbiology , 63 :208 , 1997
Abstract : Diferulate esters strengthen and cross-link primary plant cell walls and help to defend the plant from invading microbes. Phenolics also limit the degradation of plant cell walls by saprophytic microbes and by anaerobic microorganisms in the rumen. We show that incubation of wheat and barley cell walls with ferulic acid esterase from Aspergillus niger (FAE-III) or Pseudomonas fluorescens (Xy1D), together with either xylanase I from Aspergillus niger, Trichoderma viride xylanase, or xylanase from Pseudomonas fluorescens (XylA), leads to release of the ferulate dimer 5-5' diFA [(E,E)-4,4'-dihydroxy-5,5'-dimethoxy-3,3'-bicinnamic acid]. Direct saponification of the cell walls without enzyme treatment released the following five identifiable ferulate dimers (in order of abundance): (Z)-beta-(4-[(E)-2-carboxyvinyl]-2-methoxyphenoxy)-4-hydroxy-3-methoxycinnamic acid, trans-5-[(E)-2-carboxyvinyl]-2-(4-hydroxy-3-methoxy-phenyl) -7-methoxy-2, 3-dihydrobenzofuran-3-carboxylic acid, 5-5' diFA, (E,E)-4, 4'-dihydroxy-3, 5'-dimethoxy-beta, 3'-bicinnamic acid, and trans-7-hydroxy-1-(4-hydroxy-3-methoxyphenyl) -6-methoxy-1, 2-dihydronaphthalene-2, 3-dicarboxylic acid. Incubation of the wheat or barley cell walls with xylanase, followed by saponification of the solubilized fraction, yielded 5-5'diFA and, in some cases, certain of the above dimers, depending on the xylanase used. These experiments demonstrate that FAE-III and XYLD specifically release only esters of 5-5'diFA from either xylanase-treated or insoluble fractions of cell walls, even though other esterified dimers were solubilized by preincubation with xylanase. It is also concluded that the esterified dimer content of the xylanase-solubilized fraction depends on the source of the xylanase.
ESTHER : Bartolome_1997_Appl.Environ.Microbiol_63_208
PubMedSearch : Bartolome_1997_Appl.Environ.Microbiol_63_208
PubMedID: 8979352
Gene_locus related to this paper: aspni-FAEA , celju-b3pei5

Title : Specificity of an esterase (XYLD) from Pseudomonas fluorescens subsp. cellulosa - Faulds_1995_Biochim.Biophys.Acta_1243_265
Author(s) : Faulds CB , Ralet MC , Williamson G , Hazlewood GP , Gilbert HJ
Ref : Biochimica & Biophysica Acta , 1243 :265 , 1995
Abstract : Activity of an esterase from Pseudomonas fluorescens subsp. cellulosa (XYLD) on an insoluble feruloylated hemicellulose substrate (de-starched wheat bran) was dependent on the source of added endo-xylanase. The esterase exhibited high selectivity for the nature, position of linkage and size of the feruloylated oligosaccharides generated by hydrolysis of the hemicellulose. Increased affinity of XYLD with increasing size of the oligosaccharide substrate suggests that optimal activity is observed on substrates with at least 4 sugars.
ESTHER : Faulds_1995_Biochim.Biophys.Acta_1243_265
PubMedSearch : Faulds_1995_Biochim.Biophys.Acta_1243_265
PubMedID: 7873572

Title : Evidence for a general role for non-catalytic thermostabilizing domains in xylanases from thermophilic bacteria. - Fontes_1995_Biochem.J_307_151
Author(s) : Fontes CM , Hazelwood GP , Morag E , Hall J , Hirst BH , Gilbert HJ
Ref : Biochemical Journal , 307 :151 , 1995
Abstract : A genomic library of Clostridium thermocellum DNA constructed in lambda ZAPII was screened for xylanase-expressing clones. Cross-hybridization experiments revealed a new xylanase gene isolated from the gene library, which was designated xyn Y. The encoded enzyme, xylanase Y (XYLY), displayed features characteristic of an endo-beta1,4-xylanase: the enzyme rapidly hydrolysed oat spelt, wheat and rye arabinoxylans and was active against methyl-umbelliferyl-beta-D-cellobioside, but did not hydrolyse any cellulosic substrates. The pH and temperature optima of the enzyme were 6.8 and 75 degrees C respectively, and the recombinant XYLY, expressed by Escherichia coli had a maximum Mr of 116000. The nucleotide sequence of xyn Y contained an open reading frame of 3228 bp encoding a protein of predicted Mr 120 105. The encoded enzyme contained a typical N-terminal 26-residue signal peptide, followed by a 164 amino acid sequence, designated domain A, that was not essential for catalytic activity. Downstream of domain A was a 351-residue xylanase Family F catalytic domain, followed by a 180-residue sequence that exhibited 28% sequence identity with a thermostable domain of Thermoanaerobacterium saccharolyticum xylanase A. The C-terminal portion of XYLY comprised the 23-residue duplicated docking sequence found in all other C. thermocellum plant cell wall hydrolases that are constituents of the bacterium's multienzyme complex, termed the cellulosome, followed by a 286-residue domain which exhibited 32% sequence identity with the N-terminal region of C. thermocellum xylanase Z. The enzyme did not contain linker sequences found in other C. thermocellum plant cell wall hydrolases. Analysis of truncated forms of XYLY and hybrid proteins, comprising segments of XYLY fused to the E. coli maltose binding domain, confirmed that XYLY contained a central catalytic domain and an adjacent thermostable domain. The C-terminal domain did not bind to cellulose or xylan. Western blot analysis using antiserum raised against XYLY showed that the xylanase was located in the cellulosome and did not appear to be extensively glycosylated. The non-catalytic domains of XYLY are discussed in relation to the general stability of thermophilic xylanases.
ESTHER : Fontes_1995_Biochem.J_307_151
PubMedSearch : Fontes_1995_Biochem.J_307_151
PubMedID: 7717969
Gene_locus related to this paper: clotm-xyny

Title : A modular esterase from Pseudomonas fluorescens subsp. cellulosa contains a non-catalytic cellulose-binding domain - Ferreira_1993_Biochem.J_294_349
Author(s) : Ferreira LM , Wood TM , Williamson G , Faulds C , Hazlewood GP , Black GW , Gilbert HJ
Ref : Biochemical Journal , 294 ( Pt 2) :349 , 1993
Abstract : The 5' regions of genes xynB and xynC, coding for a xylanase and arabinofuranosidase respectively, are identical and are reiterated four times within the Pseudomonas fluorescens subsp. cellulosa genome. To isolate further copies of the reiterated xynB/C 5' region, a genomic library of Ps. fluorescens subsp. cellulosa DNA was screened with a probe constructed from the conserved region of xynB. DNA from one phage which hybridized to the probe, but not to sequences upstream or downstream of the reiterated xynB/C locus, was subcloned into pMTL22p to construct pFG1. The recombinant plasmid expressed a protein in Escherichia coli, designated esterase XYLD, of M(r) 58,500 which bound to cellulose but not to xylan. XYLD hydrolysed aryl esters, released acetate groups from acetylxylan and liberated 4-hydroxy-3-methoxycinnamic acid from destarched wheat bran. The nucleotide sequence of the XYLD-encoding gene, xynD, revealed an open reading frame of 1752 bp which directed the synthesis of a protein of M(r) 60,589. The 5' 817 bp of xynD and the amino acid sequence between residues 37 and 311 of XYLD were almost identical with the corresponding regions of xynB and xynC and their encoded proteins XYLB and XYLC. Truncated derivatives of XYLD lacking the N-terminal conserved sequence retained the capacity to hydrolyse ester linkages, but did not bind cellulose. Expression of truncated derivatives of xynD, comprising the 5' 817 bp sequence, encoded a non-catalytic polypeptide that bound cellulose. These data indicate that XYLD has a modular structure comprising of a N-terminal cellulose-binding domain and a C-terminal catalytic domain.
ESTHER : Ferreira_1993_Biochem.J_294_349
PubMedSearch : Ferreira_1993_Biochem.J_294_349
PubMedID: 8373350
Gene_locus related to this paper: celju-b3pei5