7P39

4,6-alpha-glucanotransferase GtfB from Limosilactobacillus reuteri NCC 2613 complexed with acarbose

Summary for 7P39

• Entry DOI: 10.2210/pdb7p39/pdb
• Related PRD ID: PRD_900022
• Descriptor: Dextransucrase, 4,6-dideoxy-4-{[(1S,4R,5S,6S)-4,5,6-trihydroxy-3-(hydroxymethyl)cyclohex-2-en-1-yl]amino}-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-beta-D-glucopyranose, CALCIUM ION, ... (5 entities in total)
• Functional Keywords: 4, 6-alpha-transglycosylation; gtfb; starch conversion, transferase
• Biological source: Lactobacillus reuteri
• Total number of polymer chains: 2
• Total formula weight: 197135.49

Authors

Pijning, T.,te Poele, E.,Gangoiti, J.,Boerner, T.,Dijkhuizen, L. (deposition date: 2021-07-07, release date: 2021-11-03, Last modification date: 2024-05-01)

Primary citation

Pijning, T.,Gangoiti, J.,Te Poele, E.M.,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., 69:13235-13245, 2021

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 ( NCC 2613) and an improved homology model of a 4,3-α-glucanotransferase GtfB ( 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.

PubMed: 34708648
DOI: 10.1021/acs.jafc.1c05657

Experimental method

X-RAY DIFFRACTION (2.9 Å)