NUCLEOTIDE-SEQUENCE OF ARFB OF CLOSTRIDIUM-STERCORARIUM, AND PREDICTION OF CATALYTIC RESIDUES OF ALPHA-L-ARABINOFURANOSIDASES BASED ON LOCAL SIMILARITY WITH SEVERAL FAMILIES OF GLYCOSYL HYDROLASES

The nucleotide sequence of the alpha-L-arabinofuranosidase gene arfB f rom Clostridium stercorarium was determined. The deduced protein has a molecular mass of 56.2 kDa with an amino terminus identical to the N- terminal sequence of the purified mature enzyme from C. stercorarium. its sequence is homologous to arabinofuranosidases of glycosyl hydrola se family 51. Sequence alignment and cluster analysis reveal three ner v members of glycosyl hydrolase family 51, allowing for the definition of highly conserved regions. Two of these regions are remarkably simi lar to the most conserved regions within several other families of gly cosyl hydrolases, which have in common a (beta/alpha)(8)-barrel as the core super-secondary structure, and allow to predict the acid/base ca talyst and the nucleophile of the active site. (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.