Reeves RA, Gibbs MD, Morris DD, Griffiths KR, Saul DJ, Bergquist PL. Sequencing and expression of additional xylanase genes from the hyperthermophile Thermotoga maritima FjSS3B.1.
Appl Environ Microbiol 2000;
66:1532-7. [PMID:
10742238 PMCID:
PMC92019 DOI:
10.1128/aem.66.4.1532-1537.2000]
[Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/1999] [Accepted: 01/10/2000] [Indexed: 11/20/2022] Open
Abstract
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.
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