A novel mechanism of xylan binding by a lectin-like module from Streptomyces lividans xylanase 10A

Autor:	Emily Amandoron, Alisdair B. Boraston, Douglas G. Kilburn, P. Tomme
Rok vydání:	2000
Předmět:	chemistry.chemical_classification animal structures biology Xylan (coating) Xylan binding Cell Biology Polysaccharide biology.organism_classification Biochemistry Streptomyces carbohydrates (lipids) Pyranose chemistry Arabinogalactan Xylanase Binding site Molecular Biology
Zdroj:	Biochemical Journal. 350:933-941
ISSN:	1470-8728 0264-6021
DOI:	10.1042/bj3500933
Popis:	The C-terminal module of xylanase 10A from Streptomyces lividans is a family 13 carbohydrate-binding module (CBM13). CBM13 binds mono- and oligo-saccharides with association constants of approximately 1x10(2) M(-1)-1x10(3) M(-1). It appears to be specific only for pyranose sugars. CBM13 binds insoluble and soluble xylan, holocellulose, pachyman, lichenan, arabinogalactan and laminarin. The association constant for binding to soluble xylan is (6.2+/-0. 6)x10(3)/mol of xylan polymer. Site-directed mutation indicates the involvement of three functional sites on CBM13 in binding to soluble xylan. The sites are similar in sequence, and are predicted to have similar structures, to the alpha, beta and gamma sites of ricin toxin B-chain, which is also in family 13. The affinity of a single binding site on CBM13 for soluble xylan is only approximately (0. 5+/-0.1)x10(3)/mol of xylan. The binding of CBM13 to soluble xylan involves additive and co-operative interactions between the three binding sites. This mechanism of binding has not previously been reported for CBMs binding polysaccharides. CBM13 is the first bacterial module from family 13 to be described in detail.
Databáze:	OpenAIRE
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