Two distinct arabinofuranosidases contribute to arabino-oligosaccharide degradation in Bacillus subtilis

Inácio, José M.; Correia, Isabel Lopes; Sá‐Nogueira, Isabel

doi:10.1099/mic.0.2008/018978-0

Cited by 60 publications

(51 citation statements)

References 45 publications

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“…The three proteins, which are encoded by the arabinose metabolic operon araABDLMNPQ-abfA, previously were shown to be dispensable for arabinose utilization in a strain bearing a large deletion comprising all genes downstream from araD (23). However, growth experiments indicated a possible involvement in the utilization of arabinose oligomers (10). To confirm this hypothesis, an in-frame deletion mutation in the araN gene was generated by allelic replacement to minimize the polar effect on the genes of the araABDLMNPQ-abfA operon, which is located downstream of araN (Fig.…”

Section: Resultsmentioning

confidence: 99%

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A Multitask ATPase Serving Different ABC-Type Sugar Importers in Bacillus subtilis

Ferreira

Sá‐Nogueira

2010

J Bacteriol

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Bacillus subtilis is able to utilize arabinopolysaccharides derived from plant biomass. Here, by combining genetic and physiological analyses we characterize the AraNPQ importer and identify primary and secondary transporters of B. subtilis involved in the uptake of arabinosaccharides. We show that the ABC-type importer AraNPQ is involved in the uptake of ␣-1,5-arabinooligosaccharides, at least up to four L-arabinosyl units. Although this system is the key transporter for ␣-1,5-arabinotriose and ␣-1,5-arabinotetraose, the results indicate that ␣-1,5-arabinobiose also is translocated by the secondary transporter AraE. This broad-specificity proton symporter is the major transporter for arabinose and also is accountable for the uptake of xylose and galactose. In addition, MsmX is shown to be the ATPase that energizes the incomplete AraNPQ importer. Furthermore, the results suggest the existence of at least one more unidentified MsmX-dependent ABC importer responsible for the uptake of nonlinear ␣-1,2-and ␣-1,3-arabinooligosaccharides. This study assigns MsmX as a multipurpose B. subtilis ATPase required to energize different saccharide transporters, the arabinooligosaccharide-specific AraNPQ-MsmX system, a putative MsmX-dependent ABC transporter specific for nonlinear arabinooligosaccharides, and the previously characterized maltodextrin-specific MdxEFGMsmX system.

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Section: Resultsmentioning

confidence: 99%

“…AraN is the BPD, and AraP and AraQ are the TMDs. This transporter, which lacks the NBD protein partner, was proposed to be involved in the uptake of arabinose oligomers mainly by genomic context and in silico analysis (10,11,23).…”

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confidence: 99%

A Multitask ATPase Serving Different ABC-Type Sugar Importers in Bacillus subtilis

Ferreira

Sá‐Nogueira

2010

J Bacteriol

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“…The resulting products, arabinose and arabinose oligomers, are transported by specific transport systems, AraE, a proton symporter, and AraNPQ, an ABCtype transporter for arabino-oligosaccharides, and presumably an additional, unidentified transporter (22). Inside the cell, arabino oligomers are further hydrolyzed by the concerted action of the two ␣-L-arabinofuranosidases (35).…”

Section: Discussionmentioning

confidence: 99%

“…Lastly, aerobic bacteria, such as Bacillus and Cellvibrio spp., secrete only a limited number of endo-type enzymes that degrade the polysaccharide backbone into relatively large oligosaccharides. The final breakdown of these oligosaccharides is carried out by cell-associated or intracellular enzymes (35,50,67). The latter strategy, which is presented elegantly in the Geobacillus spp.…”

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confidence: 99%

The l -Arabinan Utilization System of Geobacillus stearothermophilus

et al. 2011

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Geobacillus stearothermophilus T-6 is a thermophilic soil bacterium that has a 38-kb gene cluster for the utilization of arabinan, a branched polysaccharide that is part of the plant cell wall. The bacterium encodes a unique three-component regulatory system (araPST) that includes a sugar-binding lipoprotein (AraP), a histidine sensor kinase (AraS), and a response regulator (AraT) and lies adjacent to an ATP-binding cassette (ABC) arabinose transport system (araEGH). The lipoprotein (AraP) specifically bound arabinose, and gel mobility shift experiments showed that the response regulator, AraT, binds to a 139-bp fragment corresponding to the araE promoter region. Taken together, the results showed that the araPST system appeared to sense extracellular arabinose and to activate a specific ABC transporter for arabinose (AraEGH). The promoter regions of the arabinan utilization genes contain a 14-bp inverted repeat motif resembling an operator site for the arabinose repressor, AraR. AraR was found to bind specifically to these sequences, and binding was efficiently prevented in the presence of arabinose, suggesting that arabinose is the molecular inducer of the arabinan utilization system. The expression of the arabinan utilization genes was reduced in the presence of glucose, indicating that regulation is also mediated via a catabolic repression mechanism. The cluster also encodes a second putative ABC sugar transporter (AbnEFJ) whose sugar-binding lipoprotein (AbnE) was shown to interact specifically with linear and branched arabino-oligosaccharides. The final degradation of the arabino-oligosaccharides is likely carried out by intracellular enzymes, including two ␣-L-arabinofuranosidases (AbfA and AbfB), a ␤-L-arabinopyranosidase (Abp), and an arabinanase (AbnB), all of which are encoded in the 38-kb cluster.The natural degradation of biomass from plants is a key step in the carbon cycle (53,69,79). This process is carried out mainly by microorganisms that can be found either free or as part of the digestive system in higher animals (76). The three main polysaccharides in the plant cell wall are cellulose, hemicellulose, and pectin, which are rigidified by lignin, a heterogeneous aromatic polymer (28, 60). Pectin is a complex polysaccharide and may account for up to 30% of the dry weight of the plant cell wall (46). Arabinan is a pectic polysaccharide consisting of a backbone of ␣-1,5-linked L-arabinofuranosyl units, which are further decorated mainly with ␣-1,2-and ␣-1,3-linked arabinofuranosides (46).Three general strategies are taken by the microbial world for plant cell wall degradation and can be described as follows. Anaerobic bacteria, such as Clostridium spp., have evolved unique multienzyme complexes, named cellulosomes, that integrate many cellulolytic and hemicellulolytic enzymes and mediate both the attachment of the cell to the crystalline polymer and its controlled hydrolysis (9,16,23,65). Aerobic fungi, such as Trichoderma and Aspergillus, secrete a large variety of free cellulases, hemicellulases...

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“…These enzymes are two a-L-arabinofuranosidases (AbfA and AbfB) and one arabinanase (AbnB). AbfA and AbfB remove a-1,2-and a-1,3-linked arabinofuranoside substitutions [13][14][15][16][17]. The role of the araJKLMN genes in the arabinan system is not fully understood and they are likely to constitute a novel utilization pathway for pentoses in G. stearothermophilus [5,18].…”

Section: Introductionmentioning

confidence: 99%

The abp gene in Geobacillus stearothermophilus T‐6 encodes a GH27 β‐l‐arabinopyranosidase

et al. 2012

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Edited by Miguel De la RosaKeywords: b-L-Arabinopyranosidase Glycoside hydrolase family 27 Arabinopyranose Sugar beet arabinan Larch arabinogalactan 13 C NMR a b s t r a c tIn this study we demonstrate that the abp gene in Geobacillus stearothermophilus T-6 encodes a family 27 glycoside hydrolase b-L-arabinopyranosidase. The catalytic constants towards the chromogenic substrate pNP-b-L-arabinopyranoside were 0.8 ± 0.1 mM, 6.6 ± 0.3 s À1 , and 8.2 ± 0.3 s À1 mM À1for K m , k cat and k cat /K m , respectively. 13C NMR spectroscopy unequivocally showed that Abp is capable of removing b-L-arabinopyranose residues from the natural arabino-polysaccharide, larch arabinogalactan. Most family 27 enzymes are active on galactose and contain a conserved Asp residue, whereas in Abp this residue is Ile67, which shifts the specificity of the enzyme towards arabinopyranoside.

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Two distinct arabinofuranosidases contribute to arabino-oligosaccharide degradation in Bacillus subtilis

Cited by 60 publications

References 45 publications

A Multitask ATPase Serving Different ABC-Type Sugar Importers in Bacillus subtilis

A Multitask ATPase Serving Different ABC-Type Sugar Importers in Bacillus subtilis

The l -Arabinan Utilization System of Geobacillus stearothermophilus

The abp gene in Geobacillus stearothermophilus T‐6 encodes a GH27 β‐l‐arabinopyranosidase

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