Dextransucrase and the mechanism for dextran biosynthesis

Robyt, John F.; Yoon, Seung-Heon; Mukerjea, Rupendra

doi:10.1016/j.carres.2008.09.012

Cited by 110 publications

(66 citation statements)

References 51 publications

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“…The data show that, in contrast to previous proposals, only a single active site is present, and no space for a second covalently bound glucose residue or glucan polymer is available. This finding invalidates the proposal of a double active-site/double-nucleophile insertion mechanism (16). Also the conservation of key amino acids involved in substrate binding and catalysis at subsite −1 in both GH13 and GH70 enzymes confirms that the mechanism of glycosidic bond cleavage by GH70 glucansucrases is similar to that of the α-amylase superfamily enzymes (14,23).…”

Section: Discussionmentioning

confidence: 75%

“…Importantly, no evidence was obtained for a second sucrosebinding site near the active site, as required for the two catalyticsite/double-nucleophile mechanism (16). A second sucrose molecule is bound near W1531, approximately 25 Å from the catalytic site (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, the active site of GTF180-ΔN is very similar to those of GH13 family members. No space is available for a glucose covalently bound to D1136, as required for the two-nucleophile mechanism proposed by Robyt et al (16).…”

Section: Resultsmentioning

confidence: 99%

“…S1B). This mechanism requires either two nearby catalytic sites or one catalytic site with two nucleophilic residues that both form covalent glucosyl-enzyme intermediates, and that alternatingly transfer their glucosyl moiety to the C1 atom of the other covalently bound glucose, freeing that nucleophile for a next reaction cycle (16). In the absence of a three-dimensional structure of a GH70 enzyme the precise catalytic mechanism has remained controversial.…”

mentioning

confidence: 99%

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Crystal structure of a 117 kDa glucansucrase fragment provides insight into evolution and product specificity of GH70 enzymes

Vujicic-Zagar

Pijning

Kralj

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

150

262

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Glucansucrases are large enzymes belonging to glycoside hydrolase family 70, which catalyze the cleavage of sucrose into fructose and glucose, with the concomitant transfer of the glucose residue to a growing α-glucan polymer. Among others, plaque-forming oral bacteria secrete these enzymes to produce α-glucans, which facilitate the adhesion of the bacteria to the tooth enamel. We determined the crystal structure of a fully active, 1,031-residue fragment encompassing the catalytic and C-terminal domains of GTF180 from Lactobacillus reuteri 180, both in the native state, and in complexes with sucrose and maltose. These structures show that the enzyme has an α-amylase-like ðβ∕αÞ 8 -barrel catalytic domain that is circularly permuted compared to the catalytic domains of members of glycoside hydrolase families 13 and 77, which belong to the same GH-H superfamily. In contrast to previous suggestions, the enzyme has only one active site and one nucleophilic residue. Surprisingly, in GTF180 the peptide chain follows a "U"-path, such that four of the five domains are made up from discontiguous N-and C-terminal stretches of the peptide chain. Finally, the structures give insight into the factors that determine the different linkage types in the polymeric product.crystal structure complexes | exopolysaccharide | Lactobacillus reuteri | dental caries

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Section: Discussionmentioning

confidence: 75%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Crystal structure of a 117 kDa glucansucrase fragment provides insight into evolution and product specificity of GH70 enzymes

Vujicic-Zagar

Pijning

Kralj

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

150

262

View full text Add to dashboard Cite

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“…However, Streptococcus spp. does not require sucrose in the medium and produce dextransucrase constitutively (Leathers, 2002;Robyt et al, 2008). In order to find out the optimum value of sucrose for A. tropicalis dextransucrase production, different concentrations (0.5-5.0%, w/v) of sucrose were used in a medium (pH 7.0) containing (%, w/v) peptone 1.0.…”

Section: Optimization Of Substratementioning

confidence: 99%