of a Novel -Galactosidase
from the Hyperthermophilic Archaeon Sulfolobus solfataricus†
Stan J. J. Brouns,1* Nicole Smits,1
Hao Wu,1 Ambrosius P. L. Snijders,2
Phillip C. Wright,2 Willem M. de Vos,1
and John van der Oost1
Laboratory of Microbiology, Department of Agrotechnology
and Food Sciences, Wageningen
University, Hesselink van Suchtelenweg 4, 6703 CT Wageningen,
Sulfolobus solfataricus is an
aerobic crenarchaeon that thrives in acidic volcanic pools.
In this study, we have purified and characterized a thermostable
from cell extracts of S. solfataricus P2 grown
on the trisaccharide raffinose. The enzyme, designated GalS,
is highly specific for -linked
galactosides, which are optimally hydrolyzed at pH 5 and
90°C. The protein consists of 74.7-kDa subunits and
has been identified as the gene product of open reading
frame Sso3127. Its primary sequence is most related to plant
enzymes of glycoside hydrolase family 36, which are involved
in the synthesis and degradation of raffinose and stachyose.
Both the galS gene from S. solfataricus
P2 and an orthologous gene from Sulfolobus tokodaii
have been cloned
and functionally expressed in Escherichia coli,
and their activity was confirmed. At present, these Sulfolobus
enzymes not only constitute a distinct type of thermostable
within glycoside hydrolase clan D but also represent the
first members from the Archaea.
gene;Sulfolobus tokodaii;Escherichia coli;Sulfolobus;Archaea;taxonomy.
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