The carbohydrate-binding module of Fragaria x ananassa expansin 2 (CBM-FaExp2) binds to cell wall polysaccharides and decreases cell wall enzyme activities in vitro.

NARDI, C; ESCUDERO, C; MARTÍNEZ GA; CIVELLO, PM

JOURNAL OF PLANT RESEARCH

SPRINGER TOKYO

Lugar: Tokyo; Año: 2013 vol. 126 p. 151 - 159

0918-9440

A putative carbohydrate binding module (CBM) from strawberry ( Fragaria 9 ananassa Duch.) expansin 2 (CBM-FaExp2) was cloned and the encoding protein was over-expressed inEscherichia coli and purified in order to evaluate its capacity to bind different cell wallpolysaccharides "in vitro". The protein CBM-FaExp2 bound to microcrystalline cellulose, xylan and pectin with different affinities (Kad = 33.6 ± 0.44 mL g- 1,Kad =11.37 ± 0.87 mL g- 1 ,Kad = 10.4 ± 0.19 mL g- 1, respectively). According to "in vitro" enzyme assays, this CBM is able to decrease the activity of cell wall degrading enzymes such as polygalacturonase, endo-glucanase, pec-tinase and xylanase, probably because the binding of CBM-FaExp2 to the different substrates interferes with enzyme activity. The results suggest that expansins would bind not only cellulose but also a wide range of cell wall polymers.