Joana Gangoiti

• University of Groningen

GtfB-type α-glucanotransferase enzymes from glycoside hydrolase family 70 (GH70) convert starch substrates into α-glucans that are of interest as food ingredients with a low glycemic index. Characterization of several GtfBs showed that they differ in product- and substrate specificity, especially with regard to branching, but structural information...

GtfB-type glucanotransferases (GT) from GH70 act on starch and starch-derived oligosaccharides, synthesizing α-glucans. The Lactobacillus reuteri 121 4,6-α-GT synthesizes linear isomalto-maltooligosaccharides (IMMP) with up to 95% α-1,6 linked glucosyl units at the non-reducing end; its structure features a tunnel in agreement with its preference f...

The glycemic carbohydrates we consume are currently viewed in an unfavorable light in both the consumer and medical research worlds. In significant part, these carbohydrates, mainly starch and sucrose, are looked upon negatively due to their rapid and abrupt glucose delivery to the body which causes a high glycemic response. However, dietary carboh...

The fructophilic bacterium Lactobacillus kunkeei has promising applications as probiotics promoting the health of both honey bees and humans. Here, we report the synthesis of a highly branched dextran by L. kunkeei DSM 12361 and biochemical characterization of a GH70 enzyme (GtfZ). Sequence analysis revealed that GtfZ harbors two separate catalytic...

Nine GtfB-like 4,6-α-glucanotransferases (4,6-α-GTs) (represented by GtfX of L. aviarius subsp. aviarius DSM 20655) were identified to show distinct characteristics in conserved motifs I-IV. In particular, the “fingerprint” Tyr in motif III of these nine GtfB-type 4,6-α-GTs was found to be replaced by a Trp. In L. aviarius subsp. aviarius DSM20655,...

Transglucosidases belonging to the glycoside hydrolase (GH) family 70 are promising enzymatic tools for the synthesis of α-glucans with defined structures from renewable sucrose and starch substrates. Depending on the GH70 enzyme specificity, α-glucans with different structures and physicochemical properties are produced, which have found diverse (...

The Glycoside hydrolase (GH) family 70 originally was established for glucansucrases of lactic acid bacteria (LAB) converting sucrose into α-glucan polymers. In recent years we have identified 3 subfamilies of GH70 enzymes (designated GtfB, GtfC and GtfD) as 4,6-α-glucanotransferases, cleaving (α1 → 4)-linkages in maltodextrins/starch and synthesiz...

Crystal structure of the first representative of the GH70 4,6-α-glucanotransferase subfamily, showing overall structure and the main features that distinguishes it from α-amylases of GH13 and glucansucrases of GH70. Reference PDBs : 5JBD (native), 5JBF (complex with maltopentaose). See also Crystal Structure of 4,6-α-Glucanotransferase Supports Die...

Lactic acid bacteria (LAB) produce α-glucans, using glucansucrases (GSs) from glycoside hydrolase family 70 (GH70), from sucrose. It was proposed that GSs are evolutionarily linked to GH13 enzymes acting on starch-like substrates. Recently, a GH70 subfamily was discovered containing 4,6-α-glucanotransferases (4,6-α-GTs) from Lactobacilli, synthesiz...

Previously we have reported that the Gram-negative bacterium Azotobacter chroococcum NCIMB 8003 uses the 4,6-α-glucanotransferase GtfD to convert maltodextrins and starch into a reuteran-like polymer consisting of (α1→4) glucan chains connected by alternating (α1→4)/(α1→6) linkages and (α1→4,6) branching points. This enzyme constituted the single e...

GenBank accession numbers of the family GH13 and GH70 protein sequences used in the phylogenetic tree of Fig 1. Note that the GtfD-like protein encoded by Burkholderia sp. NFACC38-1 is annotated by its IMG/ER Gene ID. (TIF)

GtfD-, GtfC- and GtfB-like sequences identified via a BLASTp search using the Azotobacter chroococcum NCIMB 8003 GtfD enzyme as query. GtfD-like and GtfC-like sequences are shown in bold and lightly shaded, respectively. GtfB-like sequences are displayed in grey. (DOCX)

The fine structural features of α-glucans have been shown to drive the rate and extent of glucose release by digestive enzymes. The objective of this study was to determine the in vitro digestibility of reuteran-like α-glucan polymers produced by two novel 4,6-α-glucanotransferases from Azotobacter chroococcum (Ac) and Paenibacillus beijingensis (P...

The probiotic bacterium Lactobacillus reuteri 121 is a well-known producer of diverse homoexopolysaccharides (α-glucans and β-fructans) from sucrose and maltodextrins/starches of interest for food applications. Here, we report the draft genome sequence of this strain, with a focus on carbohydrate-active enzymes.

Food processing and refining has dramatically changed the human diet, but little is known about whether this affected the evolution of enzymes in human microbiota. We present evidence that glycoside hydrolase family 70 (GH70) glucansucrases from lactobacilli, synthesizing α-glucan-type extracellular polysaccharides from sucrose, likely evolved from...

Lactic acid bacteria possess a diversity of glucansucrase (GS) enzymes that belong to glycoside hydrolase family 70 (GH70) and convert sucrose into α-glucan polysaccharides with (α1 → 2)-, (α1 → 3)-, (α1 → 4)- and/or (α1 → 6)-glycosidic bonds. In recent years 3 novel subfamilies of GH70 enzymes, inactive on sucrose but using maltodextrins/starch as...

The human diet has been subject to dramatic changes due to food processing and refining. however, whether this affected the evolution of enzymes in human microbiota is largely unknown. It was proposed that glycoside hdyrolase family 70 (GH70) glucansucrases (GS) from Lactobacilli, which synthesize α-glucan type extracellular polysaccharides (EPS) f...

Lactic acid bacteria (LAB) are known to produce large amounts of α-glucan exopolysaccharides. Family GH70 glucansucrase (GS) enzymes catalyze the synthesis of these α-glucans from sucrose. The elucidation of the crystal structures of representative GS enzymes has advanced our understanding of their reaction mechanism, especially structural features...

Background: Originally the glycoside hydrolase (GH) family 70 only comprised glucansucrases of lactic acid bacteria which synthesize α-glucan polymers from sucrose. Recently we have identified 2 novel subfamilies of GH70 enzymes represented by the Lactobacillus reuteri 121 GtfB and the Exiguobacterium sibiricum 255-15 GtfC enzymes. Both enzymes ca...

The Glycoside Hydrolase (GH) family 70 originally was established for glucansucrase enzymes, solely found in lactic acid bacteria, synthesizing α-glucan polysaccharides from sucrose (e.g. GtfA). In recent years we have characterized GtfB and related Lactobacillus enzymes as 4,6-α-glucanotransferase enzymes. These GtfB type of enzymes constitute a f...

Nineteen medium-chain-length (mcl) poly(3-hydroxyalkanoate) (PHA)-degrading microorganisms were isolated from natural sources. From them, seven Gram-positive and three Gram-negative bacteria were identified. The ability of these microorganisms to hydrolyze other biodegradable plastics, such as short-chain-length (scl) PHA, poly(ε-caprolactone) (PCL...

The extracellular medium-chain-length polyhydroxyalkanote (MCL-PHA) depolymerase from an isolate identified as Streptomyces venezuelae SO1 was purified to electrophoretic homogeneity and characterized. The molecular mass and pI of the purified enzyme were approximately 27 kDa and 5.9, respectively. The depolymerase showed its maximum activity in th...

Several industrial processes based on lipase catalysis have been established. However, since there are still a vast number of catalytic processes that lack a suitable enzyme, the discovery of new biocatalysts is required to fulfil this purpose. The potential of using the medium-chain-length (mcl)-PHA depolymerase from Pseudomonas fluorescens GK13 i...

The extracellular medium-chain-length polyhydroxyalkanoate (MCL-PHA) depolymerase of Pseudomonas fluorescens GK13 catalyzes the hydrolysis of poly(3-hydroxyoctanoic acid) [P(3HO)]. Based on the strong tendency of the enzyme to interact with hydrophobic materials, a low-cost method which allows the rapid and easy purification and immobilization of t...