Bacteroidota polysaccharide utilization system for branched dextran exopolysaccharides from lactic acid bacteria

Nakamura, Shuntaro; Kurata, Rikuya; Tonozuka, Takashi; Funane, Kazumi; Park, Enoch Y.; Miyazaki, Takatsugu

doi:10.1016/j.jbc.2023.104885

Cited by 10 publications

(10 citation statements)

References 89 publications

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“…BT4581 produced glucose as the sole degradation product, consistent with another previously characterized Bt protein that belongs to GH97, SusB of the Sus-like system ( 42 ). On the other hand, BT3086 produced glucose and isomaltose as major degradation products, which is again consistent with products formed by exodextranases (GH31) as described previously ( 33 ). Finally, BT3087 treatment of dextran produced not only glucose and isomaltose as major degradation products but also other higher MW oligosaccharides, consistent with previous observations of studies involving GH66 endodextranases ( 33 , 35 ) ( Fig.…”

Section: Resultssupporting

confidence: 90%

“…Like starch, dextran is a polyglucan consisting of two unique glycosidic linkages: an α-1,6-linked backbone along with α-1,3 branches ( 32 ). It is known that the degradation of dextran involves the enzyme dextranase, where they may be further classified into two separate classes: endodextranase or exodextranase ( 33 ). Endodextranases (GH families 31, 49, and 66) act by randomly hydrolyzing the α-(1→6) linkages of dextran, which leads to the formation of isomaltooligosaccharides of various degrees of polymerization, whereas exodextranases (GH families 13, 15, 27, and 49) act on the non-reducing end of dextran, forming glucose, isomaltose, or isomaltotriose as the main degradation products ( 33 ).…”

Section: Introductionmentioning

confidence: 99%

“…It is known that the degradation of dextran involves the enzyme dextranase, where they may be further classified into two separate classes: endodextranase or exodextranase ( 33 ). Endodextranases (GH families 31, 49, and 66) act by randomly hydrolyzing the α-(1→6) linkages of dextran, which leads to the formation of isomaltooligosaccharides of various degrees of polymerization, whereas exodextranases (GH families 13, 15, 27, and 49) act on the non-reducing end of dextran, forming glucose, isomaltose, or isomaltotriose as the main degradation products ( 33 ). Previous works have identified the upregulation of PUL48 in Bt under dextran growth ( 30 , 34 ), which is structurally very similar to a PUL dedicated to the utilization of dextran in the Gram-negative soil bacterium Flavobacterium johnsoniae ( 33 ).…”

Section: Introductionmentioning

confidence: 99%

“…Endodextranases (GH families 31, 49, and 66) act by randomly hydrolyzing the α-(1→6) linkages of dextran, which leads to the formation of isomaltooligosaccharides of various degrees of polymerization, whereas exodextranases (GH families 13, 15, 27, and 49) act on the non-reducing end of dextran, forming glucose, isomaltose, or isomaltotriose as the main degradation products ( 33 ). Previous works have identified the upregulation of PUL48 in Bt under dextran growth ( 30 , 34 ), which is structurally very similar to a PUL dedicated to the utilization of dextran in the Gram-negative soil bacterium Flavobacterium johnsoniae ( 33 ). Both PULs featured a GH66 and a GH31, which likely serve as endodextranase and exodextranase for the hydrolysis of dextran, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Bacteroides thetaiotaomicron metabolic activity decreases with polysaccharide molecular weight

Wong,

Chillier,

Fischer-Stettler

et al. 2024

mBio

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The human colon hosts hundreds of commensal bacterial species, many of which ferment complex dietary carbohydrates. To transform these fibers into metabolically accessible compounds, microbes often express a series of dedicated enzymes homologous to the starch utilization system (Sus) encoded in polysaccharide utilization loci (PULs). The genome of Bacteroides thetaiotaomicron ( Bt ), a common member of the human gut microbiota, encodes nearly 100 PULs, conferring a strong metabolic versatility. While the structures and functions of individual enzymes within the PULs have been investigated, little is known about how polysaccharide complexity impacts the function of Sus-like systems. We here show that the activity of Sus-like systems depends on polysaccharide size, ultimately impacting bacterial growth. We demonstrate the effect of size-dependent metabolism in the context of dextran metabolism driven by the specific utilization system PUL48. We find that as the molecular weight of dextran increases, Bt growth rate decreases and lag time increases. At the enzymatic level, the dextranase BT3087, a glycoside hydrolase (GH) belonging to the GH family 66, is the main GH for dextran utilization, and BT3087 and BT3088 contribute to Bt dextran metabolism in a size-dependent manner. Finally, we show that the polysaccharide size-dependent metabolism of Bt impacts its metabolic output in a way that modulates the composition of a producer-consumer community it forms with Bacteroides fragilis . Altogether, our results expose an overlooked aspect of Bt metabolism that can impact the composition and diversity of microbiota. IMPORTANCE Polysaccharides are complex molecules that are commonly found in our diet. While humans lack the ability to degrade many polysaccharides, their intestinal microbiota contain bacterial commensals that are versatile polysaccharide utilizers. The gut commensal Bacteroides thetaiotaomicron dedicates roughly 20% of their genomes to the expression of polysaccharide utilization loci for the broad range utilization of polysaccharides. Although it is known that different polysaccharide utilization loci are dedicated to the degradation of specific polysaccharides with unique glycosidic linkages and monosaccharide compositions, it is often overlooked that specific polysaccharides may also exist in various molecular weights. These different physical attributes may impact their processability by starch utilization system-like systems, leading to differing growth rates and nutrient-sharing properties at the community level. Therefore, understanding how molecular weight impacts utilization by gut microbe may lead to the potential design of novel precision prebiotics.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Bacteroides thetaiotaomicron metabolic activity decreases with polysaccharide molecular weight

Wong,

Chillier,

Fischer-Stettler

et al. 2024

mBio

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“…These glycoside hydrolases are responsible for hydrolyzing starch and maltooligosaccharides into glucose [16][17][18]. Conversely, in the soil bacterium Flavobacterium johnsoniae, we identified a polysaccharide utilization locus (named FjDexUL) which targets branched dextran (a-(1?2)/a-(1?3)branched a-(1?6)-glucan), an exopolysaccharide produced by a lactic acid bacterium Leuconostoc citreum S-32 [19,20]. Similar to Sus, FjDexUL consists of SusR, SusC, SusD, and SusE homologs, and four glycoside hydrolases: GH66 dextranase, which degrades branched dextran extracellularly and the resultant oligosaccharides are incorporated to the periplasm, followed by hydrolysis of a-(1?6), a-(1?2), and a-(1?6)/a-(1?3) linkages by GH31 dextranase (FjDex31A), GH65 a-1,2glucosidase (FjGH65A), and GH97 a-glucoside hydrolase (FjGH97A), respectively (Fig.…”

Section: Introductionmentioning

confidence: 99%

Structural insights into α‐(1→6)‐linkage preference of GH97 glucodextranase from Flavobacterium johnsoniae

Nakamura,

Kurata,

Miyazaki

2024

The FEBS Journal

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Glycoside hydrolase family 97 (GH97) comprises enzymes like anomer‐inverting α‐glucoside hydrolases (i.e., glucoamylase) and anomer‐retaining α‐galactosidases. In a soil bacterium, Flavobacterium johnsoniae, we previously identified a GH97 enzyme (FjGH97A) within the branched dextran utilization locus. It functions as an α‐glucoside hydrolase, targeting α‐(1→6)‐glucosidic linkages in dextran and isomaltooligosaccharides (i.e., glucodextranase). FjGH97A exhibits a preference for α‐(1→6)‐glucoside linkages over α‐(1→4)‐linkages, while Bacteroides thetaiotaomicron glucoamylase SusB (with 69% sequence identity), which is involved in the starch utilization system, exhibits the highest specificity for α‐(1→4)‐glucosidic linkages. Here, we examined the crystal structures of FjGH97A in complexes with glucose, panose, or isomaltotriose, and analyzed the substrate preferences of its mutants to identify the amino acid residues that determine the substrate specificity for α‐(1→4)‐ and α‐(1→6)‐glucosidic linkages. The overall structure of FjGH97A resembles other GH97 enzymes, with conserved catalytic residues similar to anomer‐inverting GH97 enzymes. A comparison of active sites between FjGH97A and SusB revealed differences in amino acid residues at subsites +1 and +2 (specifically Ala195 and Ile378 in FjGH97A). Among the three mutants (A195S, I378F, and A195S‐I378F), A195S and A195S‐I378F exhibited increased activity toward α‐(1→4)‐glucoside bonds compared to α‐(1→6)‐glucoside bonds. This suggests that Ala195, located on the Gly184‐Thr203 loop (named loop‐N) conserved within the GH97 subgroup, including FjGH97A and SusB, holds significance in determining linkage specificity. The conservation of alanine in the active site of the GH97 enzymes, within the same gene cluster as the putative dextranase, indicates its crucial role in determining the specificity for α‐(1→6)‐glucoside linkage.

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From structure to function: A comprehensive overview of polysaccharide roles and applications

Xu,

Li,

Ding

et al. 2024

Food Frontiers

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Polysaccharides, also known as glycans, are biological macromolecules consisting of many monosaccharide units. Alongside proteins, nucleic acids, and lipids, they constitute the four fundamental substances crucial for life activities and essential for the growth and development of living organisms. As natural products with inherent biological activity, polysaccharides are widely available, nontoxic, and possess numerous functional properties, holding immense potential for advancement in food, medicine, and cosmetics. Furthermore, the exploration of polysaccharide‐based drugs, as an alternative to conventional therapies, emerges as a promising avenue for addressing future disease challenges. This article comprehensively reviews the sources, structural characteristics, synthesis, degradation, functions, and applications of polysaccharides. The potential of polysaccharides for pharmacological applications, in antitumor, antiaging, antioxidant, hypoglycemic, anti‐inflammatory, antiviral, and anticoagulant properties, is summarized. Additionally, the role of polysaccharides in environmental protection is discussed. It is anticipated that this review will offer innovative strategic insights, serving as a theoretical foundation and inspiration for the subsequent research on polysaccharides in healthcare.

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Bacteroidota polysaccharide utilization system for branched dextran exopolysaccharides from lactic acid bacteria

Cited by 10 publications

References 89 publications

Bacteroides thetaiotaomicron metabolic activity decreases with polysaccharide molecular weight

Bacteroides thetaiotaomicron metabolic activity decreases with polysaccharide molecular weight

Structural insights into α‐(1→6)‐linkage preference of GH97 glucodextranase from Flavobacterium johnsoniae

From structure to function: A comprehensive overview of polysaccharide roles and applications

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