An essential amino acid residue for catalytic activity of the dextranase of <i>Streptococcus mutans</i>

Igarashi, Takeshi; Morisaki, Hirobumi; Yamamoto, Ayako; Goto, Nobuichi

doi:10.1034/j.1399-302x.2002.170310.x

Cited by 25 publications

(36 citation statements)

References 23 publications

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“…This is consistent with the report that the mutation of S. mutans dextranase at the Asp-385, corresponding to residue 453 of S. criceti dextranase (Fig. 5B), abrogated the dextranase activity (14). As Asp-453 was shown to be critical for dextranase activity in S. criceti, this residue has been considered part of a catalytic site of dextranase.…”

Section: Discussionsupporting

confidence: 81%

“…6A and B, lane 2). This observation was consistent with the demonstration that a mutation of the Asp-385 residue of S. mutans dextranase resulted in the disappearance of the dextranase activity (14). A single codon TGG codes for a single amino acid tryptophan (Trp).…”

Section: Determination Of the Dextranase Activity Of Dextranase Mutansupporting

confidence: 75%

“…A similar finding has been made in the GH 49 family of dextranases (3). In contrast, the conserved region comprising the catalytic site and dextran-binding domain is responsible for dextranase activity (14,25). In our study, the replacement of Asp-453 with a Glu residue extinguished the activity of dextranase (Fig.…”

Section: Discussionsupporting

confidence: 59%

“…1, a dextranase catalytic site conserved in oral streptococci (13,14) was predicted in the deduced amino acid sequence of S. criceti dex. The amino acid sequence of the predicted catalytic site (position 447-458, 12 residues), FDGWQGDTIGDN, was completely conserved in other dextranases of oral streptococci (Fig.…”

Section: Nucleotide and Deduced Amino Acid Sequences Of The Dex Genementioning

confidence: 99%

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Identification and Characterization of a Dextranase Gene of Streptococcus criceti

Tamura

Yamada

Kato

2007

Microbiology and Immunology

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The dextranase gene, dex, was identified in Streptococcus criceti strain E49 by degenerate PCR and sequenced completely by the gene‐walking method. A sequence of 3,960 nucleotides was determined. The dex gene encodes a 1,200‐amino acid protein, which has a calculated molecular mass of 128,129.91 and pI of 4.15 and is predicted to be a cell‐surface protein. The deduced amino acid sequence of dex showed homology to S. downei dextranase (63.9% identity). Phylogenetic analysis revealed the similarity of the deduced amino acid sequence of dextranases in S. criceti, S. sobrinus, and S. downei. A recombinant form of the protein with six histidine residues tagged in the C‐terminus was partially purified and showed dextranase activity on blue‐dextran sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (BD‐SDS‐PAGE) followed by renaturation. We also detected dextranase activity in S. criceti cell extracts and culture supernatant by renatured BD‐SDS‐PAGE, whereas no dextranase activity of the cells was observed on blue‐dextran brain heart infusion (BD‐BHI) agar plates. Furthermore, PCR‐based mutations of dextranase indicated that a deletion mutant of the C‐terminal region could hydrolyze blue dextrans and that the D453E mutation, W793L mutation, and double mutations (W793L and deletion of the C‐terminal region) resulted in a loss of dextranase activity. These findings suggest that Asp‐453 and Trp‐793 residues of S. criceti dextranase are critical to the enzyme's activity.

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Section: Discussionsupporting

confidence: 81%

Section: Determination Of the Dextranase Activity Of Dextranase Mutansupporting

confidence: 75%

Section: Discussionsupporting

confidence: 59%

Section: Nucleotide and Deduced Amino Acid Sequences Of The Dex Genementioning

confidence: 99%

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Identification and Characterization of a Dextranase Gene of Streptococcus criceti

Tamura

Yamada

Kato

2007

Microbiology and Immunology

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“…An SDS-PAGE analysis of the recombinant enzyme indicated that there are multiple active dextranase forms (77). Comparison of the amino acid sequences of the Dex proteins and glucosyltransferases indicated that the amino acid sequences of the Dex enzymes produced by S. mutans, S. sobrinus, S. salivarius, and S. downei were similar to those of the catalytic sites of glucosyltransferases of mutans streptococci (78,137).…”

Section: Sequence Comparison Studiesmentioning

confidence: 94%

Microbial Dextran-Hydrolyzing Enzymes: Fundamentals and Applications

Khalikova

Susi

Korpela

2005

Microbiol Mol Biol Rev

228

152

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Dextran is a chemically and physically complex polymer, breakdown of which is carried out by a variety of endo- and exodextranases. Enzymes in many groups can be classified as dextranases according to function: such enzymes include dextranhydrolases, glucodextranases, exoisomaltohydrolases, exoisomaltotriohydrases, and branched-dextran exo-1,2-α-glucosidases. Cycloisomalto-oligosaccharide glucanotransferase does not formally belong to the dextranases even though its side reaction produces hydrolyzed dextrans. A new classification system for glycosylhydrolases and glycosyltransferases, which is based on amino acid sequence similarities, divides the dextranases into five families. However, this classification is still incomplete since sequence information is missing for many of the enzymes that have been biochemically characterized as dextranases. Dextran-degrading enzymes have been isolated from a wide range of microorganisms. The major characteristics of these enzymes, the methods for analyzing their activities and biological roles, analysis of primary sequence data, and three-dimensional structures of dextranases have been dealt with in this review. Dextranases are promising for future use in various scientific and biotechnological applications

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Diverse dextranase genes from Paenibacillus species

et al. 2005

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Genes encoding dextranolytic enzymes were isolated from Paenibacillus strains Dex40-8 and Dex50-2. Single, similar but non-identical dex1 genes were isolated from each strain, and a more divergent dex2 gene was isolated from strain Dex50-2. The protein deduced from the Dex40-8 dex1 gene sequence had 716 amino acids, with a predicted M(r) of 80.8 kDa. The proteins deduced from the Dex50-2 dex1 and dex2 gene sequences had 905 and 596 amino acids, with predicted M(r) of 100.1 kDa and 68.3 kDa, respectively. The deduced amino acid sequences of all three dextranolytic proteins had similarity to family 66 glycosyl hydrolases and were predicted to possess cleavable N-terminal signal peptides. Homology searches suggest that the Dex40-8 and Dex50-2 Dex1 proteins have one and two copies, respectively, of a carbohydrate-binding module similar to CBM_4_9 (pfam02018.11). The Dex50-2 Dex2 deduced amino acid sequence had highest sequence similarity to thermotolerant dextranases from thermophilic Paenibacillus strains, while the Dex40-8 and Dex50-2 Dex1 deduced protein sequences formed a distinct sequence clade among the family 66 proteins. Examination of seven Paenibacillus strains, using a polymerase chain reaction-based assay, indicated that multiple family 66 genes are common within this genus. The three recombinant proteins expressed in Escherichia coli possessed dextranolytic activity and were able to convert ethanol-insoluble blue dextran into an ethanol-soluble product, indicating they are endodextranases (EC 3.2.1.11). The reaction catalysed by each enzyme had a distinct temperature and pH dependence.

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An essential amino acid residue for catalytic activity of the dextranase of Streptococcus mutans

Cited by 25 publications

References 23 publications

Identification and Characterization of a Dextranase Gene of Streptococcus criceti

Identification and Characterization of a Dextranase Gene of Streptococcus criceti

Microbial Dextran-Hydrolyzing Enzymes: Fundamentals and Applications

Diverse dextranase genes from Paenibacillus species

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