scholarly journals The cellodextrinase from Pseudomonas fluorescens subsp. cellulosa consists of multiple functional domains

1991 ◽  
Vol 279 (3) ◽  
pp. 793-799 ◽  
Author(s):  
L M A Ferreira ◽  
G P Hazlewood ◽  
P J Barker ◽  
H J Gilbert

A genomic library of Pseudomonas fluorescens subsp. cellulosa DNA was constructed in pUC18 and Escherichia coli recombinants expressing 4-methylumbelliferyl beta-D-cellobioside-hydrolysing activity (MUCase) were isolated. Enzyme produced by MUCase-positive clones did not hydrolyse either cellobiose or cellotriose but converted cellotetraose into cellobiose and cleaved cellopentaose and cellohexaose, producing a mixture of cellobiose and cellotriose. There was no activity against CM-cellulose, insoluble cellulose or xylan. On this basis, the enzyme is identified as an endo-acting cellodextrinase and is designated cellodextrinase C (CELC). Nucleotide sequencing of the gene (celC) which directs the synthesis of CELC revealed an open reading frame of 2153 bp, encoding a protein of Mr 80,189. The deduced primary sequence of CELC was confirmed by the Mr of purified CELC (77,000) and by the experimentally determined N-terminus of the enzyme which was identical with residues 38-47 of the translated sequence. The N-terminal region of CELC showed strong homology with endoglucanase, xylanases and an arabinofuranosidase of Ps. fluorescens subsp. cellulosa; homologous sequences included highly conserved serine-rich regions. Full-length CELC bound tightly to crystalline cellulose. Truncated forms of celC from which the DNA sequence encoding the conserved domain had been deleted, directed the synthesis of a functional cellodextrinase that did not bind to crystalline cellulose. This is consistent with the N-terminal region of CELC comprising a non-catalytic cellulose-binding domain which is distinct from the catalytic domain. The role of the cellulose-binding region is discussed.

1993 ◽  
Vol 294 (2) ◽  
pp. 349-355 ◽  
Author(s):  
L M Ferreira ◽  
T M Wood ◽  
G Williamson ◽  
C Faulds ◽  
G P Hazlewood ◽  
...  

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.


1997 ◽  
Vol 323 (2) ◽  
pp. 547-555 ◽  
Author(s):  
Vincent A. McKIE ◽  
Gary W. BLACK ◽  
Sarah J. MILLWARD-SADLER ◽  
Geoffrey P. HAZLEWOOD ◽  
Judith I. LAURIE ◽  
...  

Pseudomonas fluorescens subsp. cellulosa expressed arabinanase activity when grown on media supplemented with arabinan or arabinose. Arabinanase activity was not induced by the inclusion of other plant structural polysaccharides, and was repressed by the addition of glucose. The majority of the Pseudomonas arabinanase activity was extracellular. Screening of a genomic library of P. fluorescens subsp. cellulosa DNA constructed in Lambda ZAPII, for recombinants that hydrolysed Red-dyed arabinan, identified five arabinan-degrading plaques. Each of the phage contained the same Pseudomonas arabinanase gene, designated arbA, which was present as a single copy in the Pseudomonas genome. The nucleotide sequence of arbA revealed an open reading frame of 1041 bp encoding a protein, designated arabinanase A (ArbA), of Mr 39438. The N-terminal sequence of ArbA exhibited features typical of a prokaryotic signal peptide. Analysis of the primary structure of ArbA indicated that, unlike most Pseudomonas plant cell wall hydrolases, it did not contain linker sequences or have a modular structure, but consisted of a single catalytic domain. Sequence comparison between the Pseudomonas arabinanase and proteins in the SWISS-PROT database showed that ArbA exhibits greatest sequence identity with arabinanase A from Aspergillus niger, placing the enzyme in glycosyl hydrolase Family 43. The significance of the differing substrate specificities of enzymes in Family 43 is discussed. ArbA purifed from a recombinant strain of Escherichia coli had an Mr of 34000 and an N-terminal sequence identical to residues 32–51 of the deduced sequence of ArbA, and hydrolysed linear arabinan, carboxymethylarabinan and arabino-oligosaccharides. The enzyme displayed no activity against other plant structural polysaccharides, including branched sugar beet arabinan. ArbA produced almost exclusively arabinotriose from linear arabinan and appeared to hydrolyse arabino-oligosaccharides by successively releasing arabinotriose. ArbA and the Aspergillus arabinanase mediated a decrease in the viscosity of linear arabinan that was associated with a significant release of reducing sugar. We propose that ArbA is an arabinanase that exhibits both an endo- and an exo- mode of action.


1995 ◽  
Vol 305 (3) ◽  
pp. 1005-1010 ◽  
Author(s):  
K L Braithwaite ◽  
G W Black ◽  
G P Hazlewood ◽  
B R S Ali ◽  
H J Gilbert

Pseudomonas fluorescens subsp. cellulosa when cultured in the presence of carob galactomannan degraded the polysaccharide. To isolate gene(s) from P. fluorescens subsp. cellulosa encoding endo-beta-1,4-mannanase (mannanase) activity, a genomic library of Pseudomonas DNA, constructed in lambda ZAPII, was screened for mannanase-expressing clones using the dye-labelled substrate, azo-carob galactomannan. The nucleotide sequence of the pseudomonad insert from a mannanase-positive clone revealed a single open reading frame of 1257 bp encoding a protein of M(r) 46,938. The deduced N-terminal sequence of the putative polypeptide conformed to a typical prokaryotic signal peptide. Truncated derivatives of the mannanase, lacking 54 and 16 residues from the N- and C-terminus respectively of the mature form of the enzyme, did not exhibit catalytic activity. Inspection of the primary structure of the mannanase did not reveal any obvious linker sequences or protein motifs characteristic of the non-catalytic domains located in other Pseudomonas plant cell wall hydrolases. These data indicate that the mannanase is non-modulator, comprising a single catalytic domain. Comparison of the mannanase sequence with those in the SWISSPROT database revealed greatest sequence homology with the mannanase from Bacillus sp. Thus the Pseudomonas enzyme belongs to glycosyl hydrolase Family 26, a family containing mannanases and endoglucanases. Analysis of the substrate specificity of the mannanase showed that the enzyme hydrolysed mannan and galactomannan, but displayed little activity towards other polysaccharides located in the plant cell wall. The enzyme had a pH optimum of approx. 7.0, was resistant to proteolysis and had an M(r) of 46,000 when expressed by Escherichia coli.


1995 ◽  
Vol 309 (3) ◽  
pp. 749-756 ◽  
Author(s):  
J Hall ◽  
G W Black ◽  
L M A Ferreira ◽  
S J Millward-Sadler ◽  
B R S Ali ◽  
...  

A genomic library of Pseudomonas fluorescens subsp. cellulosa DNA, constructed in lambda ZAPII, was screened for carboxymethyl-cellulase activity. The pseudomonad insert from a recombinant phage which displayed elevated cellulase activity in comparison with other cellulase-positive clones present in the library, was excised into pBluescript SK- to generate the plasmid pC48. The nucleotide sequence of the cellulase gene, designated celE, revealed a single open reading frame of 1710 bp that encoded a polypeptide, defined as endoglucanase E (CelE), of M(r) 59663. The deduced primary structure of CelE revealed an N-terminal signal peptide followed by a 300-amino-acid sequence that exhibited significant identity with the catalytic domains of cellulases belonging to glycosyl hydrolase Family 5. Adjacent to the catalytic domain was a 40-residue region that exhibited strong sequence identity to non-catalytic domains located in two other endoglucanases and a xylanase from P. fluorescens. The C-terminal 100 residues of CelE were similar to Type-I cellulose-binding domains (CBDs). The three domains of the cellulase were joined by linker sequences rich in serine residues. Analysis of the biochemical properties of full-length and truncated derivatives of CelE confirmed that the enzyme comprised an N-terminal catalytic domain and a C-terminal CBD. Analysis of purified CelE revealed that the enzyme had an M(r) of 56000 and an experimentally determined N-terminal sequence identical to residues 40-54 of the deduced primary structure of full-length CelE. The enzyme exhibited an endo mode of action in hydrolysing a range of cellulosic substrates including Avicel and acid-swollen cellulose, but did not attack xylan or any other hemicelluloses. A truncated form of the enzyme, which lacked the C-terminal CBD, displayed the same activity as full-length CelE against soluble cellulose and acid-swollen cellulose, but exhibited substantially lower activity than the full-length cellulase against Avicel. The significance of these data in relation to the role of the CBD is discussed.


1990 ◽  
Vol 272 (2) ◽  
pp. 369-376 ◽  
Author(s):  
L E Kellett ◽  
D M Poole ◽  
L M Ferreira ◽  
A J Durrant ◽  
G P Hazlewood ◽  
...  

The complete nucleotide sequence of the Pseudomonas fluorescens subsp. cellulosa xynB gene, encoding an endo-beta-1,4-xylanase (xylanase B; XYLB) has been determined. The structural gene consists of an open reading frame (ORF) of 1775 bp coding for a protein of Mr 61,000. A second ORF (xynC) of 1712 bp, which starts 148 bp downstream of xynB, encodes a protein, designated xylanase C (XYLC), of Mr 59,000. XYLB hydrolyses oat spelt xylan to xylobiose and xylose, whereas XYLC releases only arabinose from the same substrate. Thus XYLB is a typical xylanase and XYLC is an arabinofuranosidase. Both enzymes bind to crystalline cellulose (Avicel), but not to xylan. The nucleotide sequences between residues 114 and 931 of xynB and xynC were identical, as were amino acid residues 39-311 of XYLB and XYLC. This conserved sequence is reiterated elsewhere in the P. fluorescens subsp. cellulosa genome. Truncated derivatives of XYLB and XYLC, in which the conserved sequence had been deleted, retained catalytic activity, but did not exhibit cellulose binding. A hybrid gene in which the 5′ end of xynC, encoding residues 1-110 of XYLC, was fused to the Escherichia coli pho A' gene (encodes mature alkaline phosphatase) directed the synthesis of a fusion protein which exhibited alkaline phosphatase activity and bound to cellulose.


1992 ◽  
Vol 285 (3) ◽  
pp. 947-955 ◽  
Author(s):  
J E Rixon ◽  
L M A Ferreira ◽  
A J Durrant ◽  
J I Laurie ◽  
G P Hazlewood ◽  
...  

A genomic library of Pseudomonas fluorescens subsp. cellulosa DNA constructed in pUC18 and expressed in Escherichia coli was screened for recombinants expressing 4-methylumbelliferyl beta-D-glucoside hydrolysing activity (MUGase). A single MUGase-positive clone was isolated. The MUGase hydrolysed cellobiose, cellotriose, cellotetraose, cellopentaose and cellohexaose to glucose, by sequentially cleaving glucose residues from the non-reducing end of the cello-oligosaccharides. The Km values for cellobiose and cellohexaose hydrolysis were 1.2 mM and 28 microM respectively. The enzyme exhibited no activity against soluble or insoluble cellulose, xylan and xylobiose. Thus the MUGase is classified as a 1,4-beta-D-glucan glucohydrolase (EC 3.2.1.74) and is designated 1,4-beta-D-glucan glucohydrolase D (CELD). When expressed by E. coli, CELD was located in the cell-envelope fraction; a significant proportion of the native enzyme was also associated with the cell envelope when synthesized by its endogenous host. The nucleotide sequence of the gene, celD, which encodes CELD, revealed an open reading frame of 2607 bp, encoding a protein of M(r) 92,000. The deduced primary structure of CELD was confirmed by the M(r) of CELD (85,000) expressed by E. coli and P. fluorescens subsp. cellulosa, and by the experimentally determined N-terminus of the enzyme purified from E. coli, which showed identity with residues 52-67 of the celD translated sequence. The structure of the N-terminal region of full-length CELD was similar to the signal peptides of P. fluorescens subsp. cellulosa plant-cell-wall hydrolases. Deletion of the N-terminal 47 residues of CELD solubilized MUGase activity in E. coli. CELD exhibited sequence similarity with beta-glucosidase B of Clostridium thermocellum, particularly in the vicinity of the active-site aspartate residue, but did not display structural similarity with the mature forms of cellulases and xylanases expressed by P. fluorescens subsp. cellulosa.


1991 ◽  
Vol 279 (3) ◽  
pp. 787-792 ◽  
Author(s):  
D M Poole ◽  
A J Durrant ◽  
G P Hazlewood ◽  
H J Gilbert

The N-terminal 160 or 267 residues of xylanase A from Pseudomonas fluorescens subsp. cellulosa, containing a non-catalytic cellulose-binding domain (CBD), were fused to the N-terminus of the catalytic domain of endoglucanase E (EGE') from Clostridium thermocellum. A further hybrid enzyme was constructed consisting of the 347 N-terminal residues of xylanase C (XYLC) from P. fluorescens subsp. cellulosa, which also constitutes a CBD, fused to the N-terminus of endoglucanase A (EGA) from Ruminococcus albus. The three hybrid enzymes bound to insoluble cellulose, and could be eluted such that cellulose-binding capacity and catalytic activity were retained. The catalytic properties of the fusion enzymes were similar to EGE' and EGA respectively. Residues 37-347 and 34-347 of XYLC were fused to the C-terminus of EGE' and the 10 amino acids encoded by the multiple cloning sequence of pMTL22p respectively. The two hybrid proteins did not bind cellulose, although residues 39-139 of XYLC were shown previously to constitute a functional CBD. The putative role of the P. fluorescens subsp. cellulosa CBD in cellulase action is discussed.


2003 ◽  
Vol 185 (14) ◽  
pp. 4127-4135 ◽  
Author(s):  
David Mandelman ◽  
Anne Belaich ◽  
J. P. Belaich ◽  
Nushin Aghajari ◽  
Hugues Driguez ◽  
...  

ABSTRACT Complete cellulose degradation is the first step in the use of biomass as a source of renewable energy. To this end, the engineering of novel cellulase activity, the activity responsible for the hydrolysis of the β-1,4-glycosidic bonds in cellulose, is a topic of great interest. The high-resolution X-ray crystal structure of a multidomain endoglucanase from Clostridium cellulolyticum has been determined at a 1.6-Å resolution. The endoglucanase, Cel9G, is comprised of a family 9 catalytic domain attached to a family IIIc cellulose-binding domain. The two domains together form a flat platform onto which crystalline cellulose is suggested to bind and be fed into the active-site cleft for endolytic hydrolysis. To further dissect the structural basis of cellulose binding and hydrolysis, the structures of Cel9G in the presence of cellobiose, cellotriose, and a DP-10 thio-oligosaccharide inhibitor were resolved at resolutions of 1.7, 1.8, and 1.9 Å, respectively.


1999 ◽  
Vol 181 (15) ◽  
pp. 4611-4616 ◽  
Author(s):  
Helen D. Simpson ◽  
Frederic Barras

ABSTRACT The Cel5 cellulase (formerly known as endoglucanase Z) fromErwinia chrysanthemi is a multidomain enzyme consisting of a catalytic domain, a linker region, and a cellulose binding domain (CBD). A three-dimensional structure of the CBDCel5 has previously been obtained by nuclear magnetic resonance. In order to define the role of individual residues in cellulose binding, site-directed mutagenesis was performed. The role of three aromatic residues (Trp18, Trp43, and Tyr44) in cellulose binding was demonstrated. The exposed potential hydrogen bond donors, residues Gln22 and Glu27, appeared not to play a role in cellulose binding, whereas residue Asp17 was found to be important for the stability of Cel5. A deletion mutant lacking the residues Asp17 to Pro23 bound only weakly to cellulose. The sequence of CBDCel5 exhibits homology to a series of five repeating domains of a putative large protein, referred to as Yheb, from Escherichia coli. One of the repeating domains (Yheb1), consisting of 67 amino acids, was cloned from the E. coli chromosome and purified by metal chelating chromatography. While CBDCel5 bound to both cellulose and chitin, Yheb1 bound well to chitin, but only very poorly to cellulose. The Yheb protein contains a region that exhibits sequence homology with the catalytic domain of a chitinase, which is consistent with the hypothesis that the Yheb protein is a chitinase.


2003 ◽  
Vol 69 (2) ◽  
pp. 1263-1269 ◽  
Author(s):  
Yong-Soon Hwang ◽  
Eung-Soo Kim ◽  
Sándor Biró ◽  
Cha-Yong Choi

ABSTRACT To isolate a gene for stimulating avermectin production, a genomic library of Streptomyces avermitilis ATCC 31267 was constructed in Streptomyces lividans TK21 as the host strain. An 8.0-kb DNA fragment that significantly stimulated actinorhodin and undecylprodigiosin production was isolated. When wild-type S. avermitilis was transformed with the cloned fragment, avermectin production increased approximately 3.5-fold. The introduction of this fragment into high-producer (ATCC 31780) and semi-industrial (L-9) strains also resulted in an increase of avermectin production by more than 2.0- and 1.4-fold, respectively. Subclones were studied to locate the minimal region involved in stimulation of pigmented-antibiotic and avermectin production. An analysis of the nucleotide sequence of the entire DNA fragment identified eight complete and one incomplete open reading frame. All but one of the deduced proteins exhibited strong homology (68 to 84% identity) to the hypothetical proteins of Streptomyces coelicolor A3(2). The orfX gene product showed no significant similarity to any other protein in the databases, and an analysis of its sequence suggested that it was a putative membrane protein. Although the nature of the stimulatory effect is still unclear, the disruption of orfX revealed that this gene was intrinsically involved in the stimulation of avermectin production in S. avermitilis.


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