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Applied Microbiology and Biotechnology

, Volume 59, Issue 4–5, pp 455–461 | Cite as

Clostridium thermocellum cellulase CelT, a family 9 endoglucanase without an Ig-like domain or family 3c carbohydrate-binding module

  •  J. Kurokawa
  •  E. Hemjinda
  •  T. Arai
  •  T. Kimura
  •  K. Sakka
  •  K. Ohmiya
Original Paper

Abstract.

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 (CelTΔdoc) was constructed and purified from a recombinant Escherichia coli, and its enzyme properties were examined. CelTΔdoc showed strong activity toward carboxymethylcellulose (CMC) and barley β-glucan, and low activity toward xylan. The V max and K m values were 137 µmol 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.

Keywords

Cellulase Clostridium Catalytic Domain Carboxymethylcellulose Strong Activity 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  •  J. Kurokawa
    • 1
  •  E. Hemjinda
    • 1
  •  T. Arai
    • 1
  •  T. Kimura
    • 1
  •  K. Sakka
    • 1
  •  K. Ohmiya
    • 1
  1. 1.Faculty of Bioresources, Mie University, Tsu 514–8507, Japan

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