Linked Life Data

18757805

Source:http://linkedlifedata.com/resource/pubmed/id/18757805

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
Pt 9
pubmed:dateCreated
2008-9-1
pubmed:databankReference
pubmed:abstractText
Bacillus subtilis produces alpha-l-arabinofuranosidases (EC 3.2.1.55; AFs) capable of releasing arabinosyl oligomers and l-arabinose from plant cell walls. Here, we show by insertion-deletion mutational analysis that genes abfA and xsa(asd), herein renamed abf2, encode AFs responsible for the majority of the intracellular AF activity in B. subtilis. Both enzyme activities were shown to be cytosolic and functional studies indicated that arabino-oligomers are natural substrates for the AFs. The products of the two genes were overproduced in Escherichia coli, purified and characterized. The molecular mass of the purified AbfA and Abf2 was about 58 kDa and 57 kDa, respectively. However, native PAGE gradient gel analysis and cross-linking assays detected higher-order structures (>250 kDa), suggesting a multimeric organization of both enzymes. Kinetic experiments at 37 degrees C, with p-nitrophenyl-alpha-l-arabinofuranoside as substrate, gave an apparent K(m) of 0.498 mM and 0.421 mM, and V(max) of 317 U mg(-1) and 311 U mg(-1) for AbfA and Abf2, respectively. The two enzymes displayed maximum activity at 50 degrees C and 60 degrees C, respectively, and both proteins were most active at pH 8.0. AbfA and Abf2 both belong to family 51 of the glycoside hydrolases but have different substrate specificity. AbfA acts preferentially on (1-->5) linkages of linear alpha-1,5-l-arabinan and alpha-1,5-linked arabino-oligomers, and is much less effective on branched sugar beet arabinan and arabinoxylan and arabinogalactan. In contrast, Abf2 is most active on (1-->2) and (1-->3) linkages of branched arabinan and arabinoxylan, suggesting a concerted contribution of these enzymes to optimal utilization of arabinose-containing polysaccharides by B. subtilis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
1350-0872
pubmed:author
pubmed:issnType
Print
pubmed:volume
154
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2719-29
pubmed:meshHeading
pubmed-meshheading:18757805-Arabinose, pubmed-meshheading:18757805-Bacillus subtilis, pubmed-meshheading:18757805-Bacterial Proteins, pubmed-meshheading:18757805-DNA, Bacterial, pubmed-meshheading:18757805-Electrophoresis, Polyacrylamide Gel, pubmed-meshheading:18757805-Escherichia coli, pubmed-meshheading:18757805-Genes, Bacterial, pubmed-meshheading:18757805-Glycoside Hydrolases, pubmed-meshheading:18757805-Hydrogen-Ion Concentration, pubmed-meshheading:18757805-INDEL Mutation, pubmed-meshheading:18757805-Molecular Sequence Data, pubmed-meshheading:18757805-Molecular Weight, pubmed-meshheading:18757805-Plasmids, pubmed-meshheading:18757805-Polysaccharides, pubmed-meshheading:18757805-Recombinant Proteins, pubmed-meshheading:18757805-Substrate Specificity, pubmed-meshheading:18757805-Temperature, pubmed-meshheading:18757805-Xylans
pubmed:year
2008
pubmed:articleTitle
Two distinct arabinofuranosidases contribute to arabino-oligosaccharide degradation in Bacillus subtilis.
pubmed:affiliation
Laboratory of Microbial Genetics, Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, Apt 127, 2781-901 Oeiras, Portugal.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't