Download MendeleyInsights into Broad-Specificity Starch Modification from the Crystal Structure of Limosilactobacillus Reuteri NCC 2613 4,6-alpha-Glucanotransferase GtfB.
Pijning, T., Gangoiti, J., Te Poele, E.M., Borner, T., Dijkhuizen, L.(2021) J Agric Food Chem 69: 13235-13245
- PubMed: 34708648
- DOI: https://doi.org/10.1021/acs.jafc.1c05657
- Primary Citation of Related Structures:
7P38, 7P39 - PubMed Abstract:
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 is limited to a single GtfB, preferring mostly linear starches and featuring a tunneled binding groove. Here, we present the second crystal structure of a 4,6-α-glucanotransferase ( Limosilactobacillus reuteri NCC 2613) and an improved homology model of a 4,3-α-glucanotransferase GtfB ( L. fermentum NCC 2970) and show that they are able to convert both linear and branched starch substrates. Compared to the previously described GtfB structure, these two enzymes feature a much more open binding groove, reminiscent of and evolutionary closer to starch-converting GH13 α-amylases. Sequence analysis of 287 putative GtfBs suggests that only 20% of them are similarly "open" and thus suitable as broad-specificity starch-converting enzymes.
Organizational Affiliation:
Biomolecular X-ray Crystallography, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, Groningen 9747 AG, The Netherlands.
