Identification and characterization of the first β-1,3-d-xylosidase from a gram-positive bacterium, Streptomyces sp. SWU10

Publication date: Available online 10 November 2017 Source:Enzyme and Microbial Technology Author(s): Pornpimol Phuengmaung, Daisuke Fujiwara, Wasana Sukhumsirichart, Tatsuji Sakamoto In previous reports, we characterized four endo-xylanases produced by Streptomyces sp. strain SWU10 that degrade xylans to several xylooligosaccharides. To obtain a set of enzymes to achieve complete xylan degradation, a β-d-xylosidase gene was cloned and expressed in Escherichia coli, and the recombinant protein, named rSWU43A, was characterized. SWU43A is composed of 522 amino acids and does not contain a signal peptide, indicating that the enzyme is an intracellular protein. SWU43A was revealed to contain a Glyco_hydro_43 domain and possess the three conserved amino acid residues of the glycoside hydrolase family 43 proteins. The molecular mass of rSWU43A purified by Ni-affinity column chromatography was estimated to be 60kDa. The optimum reaction conditions of rSWU43A were pH 6.5 and 40°C. The enzyme was stable up to 40°C over a wide pH range (3.1–8.9). rSWU43A activity was enhanced by Fe2+ and Mn2+ and inhibited by various metals (Ag+, Cd2+, Co2+, Cu2+, Hg2+, Ni2+, and Zn2+), d-xylose, and l-arabinose. rSWU43A showed activity on p-nitrophenyl-β-d-xylopyranoside and p-nitrophenyl-α-l-arabinofuranoside substrates, with specific activities of 0.09 and 0.06U/mg, respectively, but not on any xylosidic or arabinosidic polymers. rSWU43A efficiently degraded β-1,3-xylooligosaccharides...
Source: Enzyme and Microbial Technology - Category: Biotechnology Source Type: research