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Glycoside-hydrolases in the digestive systems of lower termites
H Watanabe
National Institute
of Agrobiological Sciences, Owashi,
Tsukuba, Ibaraki, 305-8634 Japan;
Since the finding of the endogenous cellulase genes belonging to
the glycoside-hydrolase family 9 (GH9) from the termite
Reticulitermes
speratus in 1998 (Watanabe et al., 1998), we have found
expressions of
-glucosidase (GH1) in the salivary glands of the lower termiteb
Neotermes koshunensis-1,4-glucanases (Tokuda et al., 2002) andb,
endo-
cellobiohydrolase homologues (both GH7) in the hindgut
parabasalian symbionts (protozoa) (Nakashima et al., 2002;
Watanabe et al., 2002) by purification and N-terminal amino-acid
sequencing of the enzymes, and following cDNA cloning. To
elucidate further details of the lower termite digestive systems,
EST analysis was employed for mRNA extracted from the salivary
glands of R. speratus. The EST clones (about 400 at (the
submission) analyzed preliminarily encoded -glucosidase
(GH1,b-amylase (GH1, 4.7%), a-1,4-glucanase (GH9, 55.8%),
bendo-1,3-glucanase (GH16, 0.5%) and a possible protein-L-isoaspartate
O-methyltransferase (0.5%),b0.5%), but no cellobiohydrolase
homologue encoding cDNAs have not found. The result suggested
importance of protozoan cellobiohydrolase generally responsible
for degradation of crystalline region of the substrate.
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table).
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