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4,3-α-Glucanotransferase, a novel reaction specificity in glycoside hydrolase family 70 and clan GH-H

Gangoiti Muñecas, J., van Leeuwen, S. S., Gerwig, G. J., Duboux, S., Vafiadi, C., Pijning, T. & Dijkhuizen, L., 6-Jan-2017, In : Scientific Reports. 7, p. 1-15 15 p., 39761.

Research output: Contribution to journalArticleAcademicpeer-review

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 substrates, have been established (e.g. GtfB of Lactobacillus reuteri 121). Compared to the broad linkage specificity found in GSs, all GH70 starch-acting enzymes characterized so far possess 4,6-α-glucanotransferase activity, cleaving (α1 → 4)-linkages and synthesizing new (α1 → 6)-linkages. In this work a gene encoding a putative GH70 family enzyme was identified in the genome of Lactobacillus fermentum NCC 2970, displaying high sequence identity with L. reuteri 121 GtfB 4,6-α-glucanotransferase, but also with unique variations in some substrate-binding residues of GSs. Characterization of this L. fermentum GtfB and its products revealed that it acts as a 4,3-α-glucanotransferase, converting amylose into a new type of α-glucan with alternating (α1 → 3)/(α 1 → 4)-linkages and with (α1 → 3,4) branching points. The discovery of this novel reaction specificity in GH70 family and clan GH-H expands the range of α-glucans that can be synthesized and allows the identification of key positions governing the linkage specificity within the active site of the GtfB-like GH70 subfamily of enzymes.

Original languageEnglish
Article number39761
Pages (from-to)1-15
Number of pages15
JournalScientific Reports
Volume7
Publication statusPublished - 6-Jan-2017

    Keywords

  • hydrolases, Polysaccharides

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