1. Characterization of a GH Family 43 ß-Xylosidase Having a Novel Carbohydratebinding Module from Paenibacillus xylaniclasticus Strain TW1.
- Author
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Daichi Ito, Emiri Nakano, Shuichi Karita, Midori Umekawa, Ratanakhanokchai, Khanok, and Tachaapaikoon, Chakrit
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XYLOSIDASES ,ANAEROBIC bacteria ,PAENIBACILLUS ,ESCHERICHIA coli ,POLYSACCHARIDES - Abstract
Paenibacillus xylaniclasticus strain TW1, a gram-positive facultative anaerobic bacterium, was isolated as a xylanolytic microorganism from the wastes of a pineapple processing factory. A gene encoding one of its xylanolytic enzymes, a ß-xylosidase, was cloned and sequenced. Sequence analysis revealed that this ß-xylosidase, named PxXyl43A, was composed of a glycoside hydrolase (GH) family 43 subfamily 12 catalytic module and an unknown function module (UM). The full-length PxXyl43A (PxXyl43A) was heterologously expressed in Escherichia coli and purified. Recombinant PxXyl43A exhibited hydrolysis activity against both p-nitrophenyl-ß-D-xylopyranoside (pNPX) and p-nitrophenyl-a-L-arabinofuranoside at specific activities of 250 and 310 mU/mg, respectively. The optimal reaction pH and temperature for pNPX hydrolysis were 7.1 and 54 °C, respectively. At pH 7.0 and 54 °C, the Km and kcat for pNPX were 1.2 mM and 2.8 ± 0.15 s
-1 , respectively. It was also discovered that the recombinant unknown function module of PxXyl43A (PxXyl43A-UM) could bind to insoluble xylans like birchwood xylan and oat spelt xylan, whereas it did not bind to cellulosic substrates such as ball-milled cellulose, carboxymethyl cellulose or lichenan. The PxXyl43A-UM's binding constant value Ka for oat spelt xylan was 2.0 × 10-5 M-1 . These results suggest that PxXyl43A possesses a novel carbohydrate-binding module, named as CBM91, specific for xylan-containing polysaccharides. [ABSTRACT FROM AUTHOR]- Published
- 2022
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