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PDBsum entry 7bwc
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References listed in PDB file
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Key reference
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Title
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Structural insight into the substrate specificity of bombyx mori β-Fructofuranosidase belonging to the glycoside hydrolase family 32.
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Authors
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T.Miyazaki,
N.Oba,
E.Y.Park.
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Ref.
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Insect Biochem Mol Biol, 2020,
127,
103494.
[DOI no: ]
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PubMed id
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Abstract
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Sucrose-hydrolyzing enzymes are largely divided into β-fructofuranosidase and
sucrose α-glucosidase. The domestic silkworm Bombyx mori possesses both
enzymes, BmSUC1 and BmSUH, belonging to the glycoside hydrolase family 32 (GH32)
and GH13, respectively. BmSUC1 was presumed to be acquired by horizontal gene
transfer from bacteria based on phylogenetic analysis and related to tolerance
to sugar-mimic alkaloids contained in mulberry latex. Here we investigated the
substrate specificity of recombinant BmSUC1 that can hydrolyze not only sucrose
but also fructooligosaccharides and fructans, and revealed that the enzyme was
competitively inhibited by 1,4-dideoxy-1,4-imino-D-arabinitol, one of the
alkaloids. Moreover, the crystal structures of BmSUC1 in apo form and complex
with sucrose were determined, and the active site pocket was shallow and
suitable for shorter substrates but was related to more relaxed substrate
specificity than the strict sucrose α-glucosidase BmSUH. Considering together
with the distribution of BmSUC1-orthologous genes in many lepidopterans, our
results suggest that BmSUC1 contributes to the digestion of
fructooligosaccharides and fructans derived from feed plants.
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