Structural highlights
Function
[A0A1Z2RUH3_LACRE] Production of extracellular glucans, that are thought to play a key role in the development of the dental plaque because of their ability to adhere to smooth surfaces and mediate the aggregation of bacterial cells and food debris.[ARBA:ARBA00003243]
Publication Abstract from PubMed
GtfB-type alpha-glucanotransferase enzymes from glycoside hydrolase family 70 (GH70) convert starch substrates into alpha-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-alpha-glucanotransferase (Limosilactobacillus reuteri NCC 2613) and an improved homology model of a 4,3-alpha-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 alpha-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.
Insights 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 EM, Borner T, Dijkhuizen L J Agric Food Chem. 2021 Oct 28. doi: 10.1021/acs.jafc.1c05657. PMID:34708648[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Pijning T, Gangoiti J, Te Poele EM, Borner T, Dijkhuizen L. Insights into Broad-Specificity Starch Modification from the Crystal Structure of Limosilactobacillus Reuteri NCC 2613 4,6-alpha-Glucanotransferase GtfB. J Agric Food Chem. 2021 Oct 28. doi: 10.1021/acs.jafc.1c05657. PMID:34708648 doi:http://dx.doi.org/10.1021/acs.jafc.1c05657
