Engineered aryl sulfate-dependent enzymes
The present invention provides several non-naturally occurring sulfotransferase enzymes that have been engineered to react with aryl sulfate compounds as sulfo group donors, instead of the natural substrate 3′-phosphoadenosine 5′-phosphosulfate (PAPS), and with heparosan-based polysaccharides, particularly heparan sulfate, as sulfo group acceptors. Each of the engineered sulfotransferase enzymes have a biological activity characterized by the position within the heparosan-based polysaccharide that receives the sulfo group, including glucosaminyl N-sulfotransferase activity, hexuronyl 2-O sulfotransferase activity, glucosaminyl 6-O sulfotransferase activity, or glucosaminyl 3-O sulfotransferase activity. Methods of using the engineered sulfotransferases to produce sulfated heparosan-based polysaccharides, including polysaccharides having anticoagulant activity, are also provided.
1. A method of enzymatically forming a 6-O-sulfated heparan sulfate product in the absence of 3′-phosphoadenosine 5′-phosphosulfate (PAPS), the method comprising the following steps:
(a) forming a reaction mixture comprising:
(i) a sulfo group donor, the sulfo group donor consisting of an aryl sulfate compound;
(ii) heparan sulfate, wherein the heparan sulfate comprises at least one polysaccharide selected from the group consisting of N-sulfated heparan sulfate (NS-HS), N-,2-O-sulfated heparan sulfate (N,2O-HS), 2-O sulfated heparan sulfate (2O-HS), and combinations thereof, and
(iii) a non-natural glucosaminyl 6-O sulfotransferase enzyme (6OST), engineered to have sulfotransferase activity with an aryl sulfate compound as a sulfo group donor and heparan sulfate as a sulfo group acceptor,
wherein the non-natural 6OST enzyme is a mutant of a natural 6OST enzyme within enzyme class EC 2.8.2-, the natural 6OST enzyme having sulfotransferase activity with heparan sulfate and a sulfo group donor, the sulfo group donor consisting of PAPS, to form a 6-O-sulfated heparan sulfate product,
wherein the natural 6OST enzyme comprises a conserved amino acid sequence motif having the amino acid sequence, SEQ ID NO: 301, and within the amino acid sequence of the non-natural 6OST enzyme, amino acid sequence SEQ ID NO: 301 is mutated to an amino acid sequence motif selected from the group consisting of SEQ ID NO: 302, SEQ ID NO: 303, SEQ ID NO: 304, and SEQ ID NO: 305,
wherein the natural 6OST enzyme comprises a conserved amino acid sequence motif having the amino acid sequence, SEQ ID NO: 256, and within the amino acid sequence of the non-natural 6OST enzyme, amino acid sequence SEQ ID NO: 256 is mutated to an amino acid sequence motif selected from the group consisting of SEQ ID NO: 306, SEQ ID NO: 307, SEQ ID NO: 308, and SEQ ID NO: 316, and
wherein the natural 6OST enzyme comprises a conserved amino acid sequence motif having the amino acid sequence X 13 -T-R-A, wherein X 13 is any amino acid, and the non-natural 6OST enzyme comprises an amino acid sequence motif selected from the group consisting of X 13 -T-R-A, wherein X 13 is any amino acid, and a mutation to X 13 -T-X 14 -A, wherein X 13 is any amino acid and X 14 is alanine or glutamic acid;
(b) binding the aryl sulfate compound within the enzyme active site; and
(c) catalyzing the transfer of the sulfo group from the aryl sulfate compound to the heparan sulfate, thereby forming the 6-O-sulfated heparan sulfate product.
2. The method of claim 1 , wherein the amino acid sequence of the non-natural 6OST enzyme has at least 80% sequence identity with the amino acid sequence of a natural 6OST enzyme, the natural 6OST enzyme amino acid sequence selected from the group consisting of SEQ ID NO: 191, SEQ ID NO: 199, and SEQ ID NO: 201.
3. The method of claim 2 , wherein the amino acid sequence of the non-natural 6OST enzyme comprises at least one mutated amino acid sequence motif selected from the group consisting of SEQ ID NO: 303, SEQ ID NO: 304, SEQ ID NO: 305, SEQ ID NO: 306, SEQ ID NO: 307, SEQ ID NO: 308, and X 13 -T-X 14 -A, wherein X 13 is any amino acid and X 14 is alanine or glutamic acid.
4. The method of claim 2 , wherein the non-natural 6OST enzyme has an amino acid sequence selected from the group consisting of SEQ ID NO: 311, SEQ ID NO: 312, SEQ ID NO: 313, SEQ ID NO: 314 and SEQ ID NO: 315.
5. The method of claim 1 , wherein the heparan sulfate comprises NS-HS.
6. The method of claim 1 , wherein the heparan sulfate comprises N,2O-HS, and the 6-O-sulfated heparan sulfate product comprises N-,2-O,6-O-sulfated heparan sulfate (N,2O,6O-HS).
7. The method of claim 6 , wherein the N,2O,6O-HS product comprises at least one polysaccharide comprising a sequence motif having the structure of Formula X, below:
wherein X is either a sulfo group or an acetate group, and Y is either a sulfo group or a hydroxyl group.
8. The method of claim 1 , wherein the aryl sulfate compound is selected from the group consisting of p-nitrophenyl sulfate and 4-nitrocatechol sulfate.
9. A non-natural glucosaminyl 6-O sulfotransferase enzyme (6OST) enzyme having an amino acid sequence comprising multiple mutations relative to conserved amino acid residues and sequence motifs found in natural 6OST enzymes within enzyme class EC 2.8.2-,
wherein the natural 6OST enzyme comprises a conserved amino acid sequence motif having the amino acid sequence, SEQ ID NO: 301, and within the amino acid sequence of the non-natural 6OST enzyme, amino acid sequence SEQ ID NO: 301 is mutated to an amino acid sequence motif selected from the group consisting of SEQ ID NO: 302, SEQ ID NO: 303, SEQ ID NO: 304, and SEQ ID NO: 305,
wherein the natural 6OST enzyme comprises a conserved amino acid sequence motif having the amino acid sequence, SEQ ID NO: 256, and within the amino acid sequence of the non-natural 6OST enzyme, amino acid sequence SEQ ID NO: 256 is mutated to an amino acid sequence motif selected from the group consisting of SEQ ID NO: 306, SEQ ID NO: 307, SEQ ID NO: 308, and SEQ ID NO: 316,
wherein the natural 6OST enzyme comprises a conserved amino acid sequence motif having the amino acid sequence X 13 -T-R-A, wherein X 13 is any amino acid, and the non-natural 6OST enzyme comprises an amino acid sequence motif selected from the group consisting of X 13 -T-R-A, wherein X 13 is any amino acid, and a mutation to X 13 -T-X 14 -A, wherein X 13 is any amino acid and X 14 is alanine or glutamic acid, and
wherein in the absence of 3′-phosphoadenosine 5′-phosphosulfate (PAPS), the non-natural 6OST enzyme has sulfotransferase activity with an aryl sulfate compound as a sulfo group donor and heparan sulfate as a sulfo group acceptor to form a 6-O-sulfated heparan sulfate product.
10. The non-natural 6OST enzyme of claim 9 , wherein the amino acid sequence of the non-natural 6OST enzyme has at least 80% sequence identity with the amino acid sequence of a natural 6OST enzyme, the natural 6OST enzyme amino acid sequence selected from the group consisting of SEQ ID NO: 191, SEQ ID NO: 199, and SEQ ID NO: 201.
11. The non-natural 6OST enzyme of claim 10 , wherein the amino acid sequence of the non-natural 6OST enzyme comprises at least one mutated amino acid sequence motif selected from the group consisting of SEQ ID NO: 303, SEQ ID NO: 304, SEQ ID NO: 305, SEQ ID NO: 306, SEQ ID NO: 307, SEQ ID NO: 308, and X 13 -T-X 14 -A, wherein X 13 is any amino acid and X 14 is alanine or glutamic acid.
12. The non-natural 6OST enzyme of claim 10 , wherein the non-natural 6OST enzyme has an amino acid sequence selected from the group consisting of SEQ ID NO: 311, SEQ ID NO: 312, SEQ ID NO: 313, SEQ ID NO: 314 and SEQ ID NO: 315.
13. The non-natural 6OST enzyme of claim 9 , wherein the aryl sulfate compound is selected from the group consisting of p-nitrophenyl sulfate and 4-nitrocatechol sulfate.
14. A nucleic acid molecule comprising a nucleotide sequence encoding for the non-natural 6OST enzyme of claim 9 .
15. The nucleic acid molecule of claim 14 , wherein the nucleotide sequence is comprised within an expression vector.
16. The nucleic acid molecule of claim 15 , wherein the expression vector is comprised within an isolated host cell, selected from the group consisting of a bacterial cell, a yeast cell, an insect cell, and a mammalian cell.
17. The nucleic acid molecule of claim 16 , wherein the isolated host cell is a yeast cell.
18. The nucleic acid molecule of claim 17 , wherein the yeast cell is a Pichia pastoris cell.
19. The nucleic acid molecule of claim 15 , wherein the expression vector encodes for a fusion protein comprising the non-natural 6OST enzyme and one or more additional polypeptides.