Sequencing and expression of additional xylanase genes from the hyperthermophile Thermotoga maritima FjSS3B.1.
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.
Reeves
R A
RA
Department of Biological Sciences, Macquarie University, Sydney New South Wales, Australia, New Zealand.
Gibbs
M D
MD
Morris
D D
DD
Griffiths
K R
KR
Saul
D J
DJ
Bergquist
P L
PL
D001419:Bacteria / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D015139:Blotting, Southern; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013696:Temperature; D014871:Water Microbiology; D043325:Xylan Endo-1,3-beta-Xylosidase; D014995:Xylosidases / Q000235:genetics* / Q000378:metabolism*
D001426:Bacterial Proteins; D011994:Recombinant Proteins; D014995:Xylosidases; D043325:Xylan Endo-1,3-beta-Xylosidase