Love D R, Fisher R, Bergquist P L
Department of Cell Biology, University of Auckland, Private Bag, New Zealand.
Mol Gen Genet. 1988 Jul;213(1):84-92. doi: 10.1007/BF00333402.
The gene for a beta-glucosidase from the extremely thermophilic bacterium Caldocellum saccharolyticum has been isolated from a genomic library and sequenced. An open reading frame identified by computer analysis of the sequence could encode a protein of Mr 54,400, which is close to the size of the polypeptide experimentally determined using maxicells. Analysis of the amino-terminal residues of the protein produced in Escherichia coli suggests that it is processed by a methionine aminopeptidase. A sequence within C. saccharolyticum DNA upstream of the beta-glucosidase gene was found to act as a promoter for expression of the thermophile gene in E. coli. The protein has been overproduced in E. coli and Bacillus subtilis where it retains its enzymatic activity and heat stability. There appears to be a single copy of the gene in Caldocellum DNA.
已从嗜热栖热放线菌的基因组文库中分离出编码β-葡萄糖苷酶的基因并进行了测序。通过对该序列进行计算机分析确定的一个开放阅读框可编码一个分子量为54400的蛋白质，这与使用最大细胞法实验测定的多肽大小相近。对在大肠杆菌中产生的该蛋白质的氨基末端残基进行分析表明，它是由甲硫氨酸氨肽酶加工而成的。发现在β-葡萄糖苷酶基因上游的嗜热栖热放线菌DNA中的一个序列可作为该嗜热菌基因在大肠杆菌中表达的启动子。该蛋白质已在大肠杆菌和枯草芽孢杆菌中过量表达，在这些宿主中它保留了酶活性和热稳定性。嗜热栖热放线菌的DNA中似乎只有该基因的一个拷贝。
