A novel beta-N-acetylglucosaminidase from Streptomyces thermoviolaceus OPC-520: Gene cloning, expression, and assignment to family 3 of the glycosyl hydrolases

作者：Tsujibo H^*; Hatano N; Mikami T; Hirasawa A; Miyamoto K; Inamori Y

来源：Applied and Environmental Microbiology, 1998, 64(8): 2920-2924.

DOI：10.1128/aem.64.8.2920-2924.1998

A beta-N-acetylglucosaminidase gene (nagA) of Streptomyces thermoviolaceus OPC-520 was cloned in Streptomyces lividans 66. The nucleotide sequence of the gene, which encodes NagA, revealed are open reading frame of 1,896 bp, encoding a protein with an M-r of 66,329. The deduced primary structure of NagA was confirmed by comparison with the N-terminal amino acid sequence of the cloned beta-N-acetylglucosaminidase expressed by S. lividans. The enzyme shares no sequence similarity with the classical beta-N-acetylglucosaminidases belonging to family 20. However, NagA, which showed no detectable beta-glucosidase activity, revealed homology with microbial beta-glucosidases belonging to family 3; in particular, striking homology with the active-site regions of beta-glucosidases was observed. Thus, the above-mentioned results indicate that NagA Born S. thermoviolaceus OPC-520 is classified as a family 3 glycosyl hydrolase. The enzyme activity was optimal at 60 degrees C and pH 5.0, and the apparent K-m and V-max values for p-nitrophenyl-beta-N-acetylglycosamine were 425.7 mu M and 24.8 mu mol min(-1) mg of protein(-1), respectively.

• 出版日期1998-8