Diverse genes of cellulase homologues of glycosyl hydrolase family 45 from the symbiotic protists in the hindgut of the termite Reticulitermes speratus |
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Authors: | Kuniyo Ohtoko M Ohkuma Shigeharu Moriya Tetsushi Inoue Ron Usami Toshiaki Kudo |
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Institution: | (1) RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama 351-0198, Japan Tel. +81-48-467-9545; Fax +81-48-462-4672 e-mail: mohkuma@mailman.riken.go.jp, JP;(2) Department of Applied Chemistry, Toyo University, Saitama, Japan, JP;(3) Japan Science and Technology Corporation, Saitama, Japan, JP |
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Abstract: | Diverse genes encoding cellulase homologues belonging to glycosyl hydrolase family 45 were identified from the symbiotic
protists in the hindgut of the termite Reticulitermes speratus through the use of consensus PCR and the screening of a cDNA library. Fifteen full-length cDNA clones were isolated and sequenced,
which encoded polypeptides consisting of 218–221 amino acid residues showing up to 63% identity to known family 45 cellulases.
The cellulase sequences of the termite symbiotic protists were phylogenetically monophyletic, showing more than 75% amino
acid identity with each other. These enzymes consist of a single catalytic domain, lacking the ancillary domains found in
most microbial cellulases. By whole-cell in situ hybridization using oligonucleotide probes specific for regions conserved
in some of the sequences, the origin of the genes was identified as symbiotic hypermastigote protists. The presence of diverse
cellulase homologues suggests that symbiotic protists of termites may be rich reservoirs of novel cellulase sequences.
Received: July 10, 2000 / Accepted: August 15, 2000 |
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Keywords: | Cellulase Protist Early-branching eukaryote Symbiosis Termite |
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