Sequencing and expression of additional xylanase genes from the hyperthermophile Thermotoga maritima FjSS3B.1

• Published in: Applied and environmental microbiology 2000-04, Vol.66 (4), p.1532-1537
• Main Authors: REEVES, R. A, GIBBS, M. D, MORRIS, D. D, GRIFFITHS, K. R, SAUL, D. J, BERGQUIST, P. L
• Format: Article
• Language: English
• Subjects: Bacteria - enzymology; Bacteria - genetics; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Blotting, Southern; Cloning, Molecular; Electrophoresis, Polyacrylamide Gel; Enzymes; Fundamental and applied biological sciences. Psychology; Genes; Genes, Bacterial; Genetics; Microbiology; Mission oriented research; Molecular Sequence Data; Physiology and Biotechnology; Polymerase Chain Reaction; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Sequence Analysis, DNA; Temperature; Thermotoga maritima; Water Microbiology; xylan; Xylan Endo-1,3-beta-Xylosidase; Xylosidases - genetics; Xylosidases - metabolism; XynA protein; xynB gene; XynB protein; xynC gene; XynC protein
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.66.4.1532-1537.2000

Two genes, xynB and xynC, coding for xylanases were isolated from Thermotoga maritima FjSS3B.1 by a genomic-walking-PCR technique. Sequencing of the genes showed that they encode multidomain family 10 xylanases. Only XynB exhibited activity against xylan substrates. The temperature optimum (87 degrees C) and pH optimum (pH 6.5) of XynB are different from the previously reported xylanase, XynA (also a family 10 enzyme), from this organism. The catalytic domain expressed without other domains has a lower temperature optimum, is less thermostable, and has optimal activity at pH 6.5. Despite having a high level of sequence similarity to xynB, xynC appears to be nonfunctional since its encoded protein did not show significant activity on xylan substrates.