Clostridium thermocellum cellulase CelT, a family 9 endoglucanase without an Ig-like domain or family 3c carbohydrate-binding module.
The celT gene of Clostridium thermocellum strain F1 was found downstream of the mannanase gene man26B [Kurokawa J et al. (2001) Biosci Biotechnol Biochem 65:548-554] in pKS305. The open reading frame of celT consists of 1,833 nucleotides encoding a protein of 611 amino acids with a predicted molecular weight of 68,510. The mature form of CelT consists of a family 9 cellulase domain and a dockerin domain responsible for cellulosome assembly, but lacks a family 3c carbohydrate-binding module (CBM) and an immunoglobulin (Ig)-like domain, which are often found with family 9 catalytic domains. CelT devoid of the dockerin domain (CelTDeltadoc) was constructed and purified from a recombinant Escherichia coli, and its enzyme properties were examined. CelTDeltadoc showed strong activity toward carboxymethylcellulose (CMC) and barley beta-glucan, and low activity toward xylan. The V(max) and K(m) values were 137 micro mol min(-1) mg(-1) and 16.7 mg/ml, respectively, for CMC. Immunological analysis indicated that CelT is a catalytic component of the C. thermocellum F1 cellulosome. This is the first report describing the characterization of a family 9 cellulase without an Ig-like domain or family 3c CBM.
Kurokawa
J
J
Faculty of Bioresources, Mie University, Tsu 514-8507, Japan.
Hemjinda
E
E
Arai
T
T
Kimura
T
T
Sakka
K
K
Ohmiya
K
K
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D015153:Blotting, Western; D050260:Carbohydrate Metabolism; D002266:Carboxymethylcellulose Sodium / Q000378:metabolism; D002480:Cellulase / Q000737:chemistry* / Q000145:classification* / Q000235:genetics / Q000378:metabolism; D003013:Clostridium / Q000201:enzymology* / Q000235:genetics; D005936:Glucans / Q000378:metabolism; D001467:Hordeum / Q000737:chemistry; D007136:Immunoglobulins / Q000737:chemistry; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA
D001426:Bacterial Proteins; D005936:Glucans; D007136:Immunoglobulins; D011994:Recombinant Proteins; D002480:Cellulase; D002266:Carboxymethylcellulose Sodium