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 CRISTINA F.; ESCUDERO CRISTIAN M.; VILLARREAL N.; MARTÍNEZ GUSTAVO A.; CIVELLO P.

JOURNAL OF PLANT RESEARCH

SPRINGER TOKYO

Lugar: Tokyo; Año: 2012

0918-9440

Abstract A putative carbohydrate binding module (CBM) from strawberry (Fragaria x 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.