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Sabree ZL,
Bergendahl V,
Liles MR,
Burgess RR,
Goodman RM,
Handelsman J,
( 2006 ) Identification and characterization of the gene encoding the Acidobacterium capsulatum major sigma factor. PMID : 16698197 : DOI : 10.1016/j.gene.2006.02.033 Abstract >>
Acidobacterium capsulatum is an acid-tolerant, encapsulated, Gram-negative member of the ubiquitous, but poorly understood Acidobacteria phylum. Little is known about the genetics and regulatory mechanisms of A. capsulatum. To begin to address this gap, we identified the gene encoding the A. capsulatum major sigma factor, rpoD, which encodes a 597-amino acid protein with a predicted sequence highly similar to the major sigma factors of Solibacter usitatus Ellin6076 and Geobacter sulfurreducens PCA. Purified hexahistidine-tagged RpoD migrates at approximately 70 kDa under SDS-PAGE conditions, which is consistent with the predicted MW of 69.2 kDa, and the gene product is immunoreactive with monoclonal antibodies specific for either bacterial RpoD proteins or the N-terminal histidine tag. A. capsulatum RpoD restored normal growth to E. coli strain CAG20153 under conditions that prevent expression of the endogenous rpoD. These results indicate we have cloned the gene encoding the A. capsulatum major sigma factor and the gene product is active in E. coli.
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( 1998 ) Gene cloning and characterization of an acidic xylanase from Acidobacterium capsulatum. PMID : 9692186 : DOI : 10.1271/bbb.62.1061 Abstract >>
The gene xynA encoding an acid endo-beta-1,4-xylanase from an acidophilic bacterium, Acidobacterium capsulatum 161, was cloned and expressed in Eschrichia coli. The nucleotide sequence of the 1.6-kb DNA fragment containing xynA was analyzed, revealing an open reading frame of 1,215 bp encoding a peptide of 405 amino acid residues. The deduced amino acid sequence of XynA was very similar to other xylanases that are from the glycosyl hydrolase family 10. XynA was purified to homogeneity by SDS-polyacrylamide gel electrophoresis from E. coli transformants. The molecular mass and isoelectric point of XynA were 41 kDa and 7.3, respectively. The xylanase activity of the cloned XynA is an endo-acting enzyme that shows optimal activity at pH 5.0 and 65 degrees C, and is stable pH between 3.0 and 8.0. The K(m) and Vmax with oat spelt xylan as a substrate at pH 5.0 and 30 degrees C are 3.5 mg/ml and 403 mumol/min/mg.
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