Beta-galactosidase variant having high transglycosylation activity, and use thereof
The present invention relates to a beta-galactosidase mutant having high transglycosylation activity and containing a C-terminal deletion, and the use thereof and more. More specifically, the present invention relates to a beta-galactosidase mutant having a C-terminal deletion, a gene encoding the same, a recombinant vector containing the gene, a recombinant microorganism transformed with the gene or the recombinant vector, and a method for producing the beta-galactosidase mutant using the recombinant microorganism. Using the high transglycosylation activity of the beta-galactosidase mutant containing the C-terminal deletion according to the present invention, galactooligosaccharide can be efficiently produced in large amounts.
1. A beta-galactosidase mutant having improved thermal stability or enzymatic activity compared to a wild-type beta-galactosidase set forth in the amino acid sequence of SEQ ID NO: 3 by deleting C-terminus of a beta-galactosidase set forth in the amino acid sequence of SEQ ID NO: 3, wherein the deletion of C-terminus is one or more selected from the group consisting of:
a) a C-terminal deletion mutation after amino acid residue 799;
b) a C-terminal deletion mutation after amino acid residue 873;
c) a C-terminal deletion mutation after amino acid residue 950;
d) a C-terminal deletion mutation alter amino acid residue 1000;
e) a C-terminal deletion mutation after amino acid residue 1059;
f) a C-terminal deletion mutation after amino acid residue 1066;
g) a C-terminal deletion mutation after amino acid residue 1115;
h) a C-terminal deletion mutation after amino acid residue 1164;
i) a C-terminal deletion mutation after amino acid residue 1302; and
j) a C-terminal deletion mutation after amino acid residue 1350.
2. The beta-galactosidase mutant of claim 1 , wherein the amino acid sequence of the mutant is SEQ ID NOs: 4, 6, 10, 12, 14, 16, 18, 20, 24 or 26.
3. A gene encoding a beta-galactosidase mutant of claim 1 .
4. A recombinant microorganism into which the gene of claim 3 or a recombinant vector comprising the gene of claim 3 is introduced.
5. The recombinant microorganism of claim 4 , wherein said microorganism is Bacillus subtillis.
6. A method for producing a beta-galactosidase mutant, comprising the steps of:
expressing the beta-galactosidase mutant by culturing the recombinant microorganism of claim 4 ; and
recovering the expressed beta-galactosidase mutant.
7. A method for producing a galactooligosaccharide, comprising:
reacting a lactose-containing substrate with a beta-galactosidase mutant of claim 1 to produce galactooligosaccharide; and
recovering the produced galactooligosaccharide.