Effect of carbohydrate-binding module of strawberry expansin2 (CBM-FaExp2) on in vitro hydrolytic activity of cell wall enzymes

CRISTINA F. NARDI; CRISTIAN ESCUDERO; NATALIA VILLARREAL; GUSTAVO MARTINEZ; MARCOS CIVELLO

JOURNAL OF PLANT RESEARCH

SPRINGER TOKYO

Lugar: Tokyo; Año: 2012 vol. 126 p. 151 - 159

0918-9440

Abstract 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 in Escherichia coli and purified in order to evaluate its capacity to bind different cell wall polysaccharides ??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, pectinase and xylanase, probably because the binding of CBMFaExp2 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.