Publication Date:
2016-04-20
Description:
A β-glycoside hydrolase was isolated from cell walls material in Coprinopsis cinerea elongating stipes. By analysis of SDS-PAGE, MALDI-TOF/TOF MS and substrate specificity, this enzyme was characterized as an extracellular β-glucosidase which is a trimer consisting of three homosubunits. β-Glucosidase did not degrade β-glucans with modified ends, whereas it hydrolyzed various β-glucans with free ends and related oligosaccharides with β-1,3-, β-1,4- or β-1,6-linkages. Although this β-glucosidase possesses glycosyltransferase activity on laminarioligosaccharides, it did not transfer glucose residues from laminaritriose to β-glucan in stipe cell walls to produce larger β-glucan molecules; instead, it caused a decrease in the molecular size of stipe wall β-glucan by removing glucose. Relatively, the molecular size of wall β-glucans in the elongating apical stipe was less than that found in the non-elongating basal stipes, and this β-glucosidase was more highly expressed in the elongating apical stipe than in non-elongating basal regions. Therefore, we propose that β-glucosidase functions by trimming or cutting the β-glucan side chains on the β-1,3-glucan backbone to prevent them from forming longer branches, keeping the wall plastic to promote diffuse wall growth.
Keywords:
Physiology & Biochemistry
Print ISSN:
0378-1097
Electronic ISSN:
1574-6968
Topics:
Biology
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