Characterization of a gene encoding cellulase from uncultured soil bacteria.
To detect cellulases encoded by uncultured microorganisms, we constructed metagenomic libraries from Korean soil DNAs. Screenings of the libraries revealed a clone pCM2 that uses carboxymethyl cellulose (CMC) as a sole carbon source. Further analysis of the insert showed two consecutive ORFs (celM2 and xynM2) encoding proteins of 226 and 662 amino acids, respectively. A multiple sequence analysis with the deduced amino acid sequences of celM2 showed 36% sequence identity with cellulase from the Synechococcus sp., while xynM2 had 59% identity to endo-1,4-beta-xylanase A from Cellulomonas pachnodae. The highest enzymatic CMC hydrolysis was observable at pH 4.0 and 45 degrees C with recombinant CelM2 protein. Although the enzyme CelM2 additionally hydrolyzed avicel and xylan, no substrate hydrolysis was observed on oligosaccharides such as cellobiose, pNP-beta-cellobioside, pNP-beta-glucoside, and pNP-beta-xyloside. These results showed that CelM2 is a novel endo-type cellulase.
Kim
Soo-Jin
SJ
Microbial Genetics Division, National Institute of Agricultural Biotechnology, Rural Development Administration, Suwon, Korea.
Lee
Chang-Muk
CM
Han
Bo-Ram
BR
Kim
Min-Young
MY
Yeo
Yun-Soo
YS
Yoon
Sang-Hong
SH
Koo
Bon-Sung
BS
Jun
Hong-Ki
HK
D000595:Amino Acid Sequence; D001419:Bacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D002266:Carboxymethylcellulose Sodium / Q000378:metabolism; D002480:Cellulase / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D015698:Genomic Library; D007723:Korea; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013379:Substrate Specificity
D001426:Bacterial Proteins; D002480:Cellulase; D002266:Carboxymethylcellulose Sodium