A new thermostable alpha-L-arabinofuranosidase from a novel thermophilic bacterium.
An alpha-L-arabinofuranosidase gene was identified in a sequenced genome of a novel thermophilic bacterium, which belongs to the recently described phylum of Thermomicrobia. Amino acid sequence comparison of the enzyme (designated AraF) revealed similarity to glycoside hydrolases of family 51. The gene was cloned into Escherichia coli and its recombinant product expressed and purified. The enzyme appeared to be a hexamer. AraF was optimally active at 70 degrees C (over 10 min) and pH 6 having 92% residual activity after 1 h at 70 degrees C. AraF had a Km) value of 0.6 mM and V(max) value of 122 U mg(-1) on p-nitrophenyl-alpha-L-arabinofuranoside. AraF was almost equally active on branched arabinan and debranched arabinan, properties not previously found in alpha-L-arabinofuranosidases in GH family 51.
Birgisson
Hákon
H
Prokaria Ltd., Gylfaflöt 5, 112 Reykjavik, Iceland. hakon.birgisson@prokaria.com
Fridjonsson
Olafur
O
Bahrani-Mougeot
Farah Khadijeh
FK
Hreggvidsson
Gudmundur O
GO
Kristjansson
Jakob K
JK
Mattiasson
Bo
B
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D041862:Chloroflexi / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D015870:Gene Expression; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D011134:Polysaccharides / Q000737:chemistry*; D013379:Substrate Specificity
D001426:Bacterial Proteins; D011134:Polysaccharides; C030080:araban; D006026:Glycoside Hydrolases; C019713:alpha-N-arabinofuranosidase