Analyses of the gene and amino acid sequence of the Prevotella (Bacteroides) ruminicola 23 xylanase reveals unexpected homology with endoglucanases from other genera of bacteria.
The DNA sequence for the xylanase gene from Prevotella (Bacteroides) ruminicola 23 was determined. The xylanase gene encoded for a protein with a molecular weight of 65,740. An apparent leader sequence of 22 amino acids was observed. The promoter region for expression of the xylanase gene in Bacteroides species was identified with a promoterless chloramphenicol acetyltransferase gene. A region of high amino acid homology was found with the proposed catalytic domain of endoglucanases from several organisms, including Butyrivibrio fibrisolvens, Ruminococcus flavefaciens, and Clostridium thermocellum. The cloned xylanase was found to exhibit endoglucanase activity against carboxymethyl cellulose. Analysis of the codon usage for the xylanase gene found a bias towards G and C in the third position in 16 of 18 amino acids with degenerate codons.
Whitehead
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National Center for Agricultural Utilization Research, United States Department of Agriculture, Peoria, Illinois 61604.
D000595:Amino Acid Sequence; D001421:Bacteria, Anaerobic / Q000201:enzymology*; D001439:Bacteroides / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D002480:Cellulase / Q000235:genetics*; D003062:Codon / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D006026:Glycoside Hydrolases / Q000235:genetics*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D043325:Xylan Endo-1,3-beta-Xylosidase
D003062:Codon; D004269:DNA, Bacterial; D006026:Glycoside Hydrolases; D043325:Xylan Endo-1,3-beta-Xylosidase; D002480:Cellulase