Engineered botulinum neurotoxin

1. A polypeptide comprising a modified receptor binding domain of Clostridial botulinum serotype B (B-H c ) comprising an amino acid substitution mutation at the amino acid position E1191 of the polypeptide of SEQ ID NO: 4 with M, Q, C, V, Y, T or I, wherein the substitution mutation produces enhanced binding of the modified B-H c to human SytII as compared to an identical molecule lacking the substitution mutation.

2. The polypeptide of claim 1 that is a botulinum neurotoxin (BoNT) polypeptide comprising:

a) a protease domain;

b) a protease cleavage site;

c) a translocation domain; and

d) the modified receptor binding domain of Clostridial botulinum serotype B (B-H c .

3. The polypeptide of claim 1 , further comprising one or more amino acid substitution mutations at an amino acid position of the SEQ ID NO: 4, selected from the group consisting of:

substitution of E, H, Y, W, F, or L at S1199;

substitution of Q, Y, A or S at W1178;

substitution of C, P, or M at Y1183;

substitution of S, M or Y at P1117;

substitution of V at S1201;

substitution of M at V1118;

substitution of Y at A1196;

substitution of M at Y1181; and combinations thereof.

4. The polypeptide of claim 1 , wherein the modified (B-H c ) comprises two substitution mutations.

5. The polypeptide of claim 4 wherein the two substitution mutations correspond to

E1191M and S1199Y;

E1191M and S1199W;

E1191M and S1199L;

E1191M and S1199Y;

E1191M and S1199F;

E1191Q and S1199Y;

E1191Q and S1199W;

E1191Q and S1199L;

E1191Q and S1199Y;

E1191Q and S1199F;

E1191C and S1199Y;

E1191C and S1199W;

E1191V and S1199Y;

E1191V and S1199W;

E1191M and W1178Q;

E1191Q and W1178Q;

E1191C and W1178Q; or

E1191V and W1178Q.

6. The polypeptide of claim 1 , wherein the substitution mutation is a non-naturally occurring amino acid.

7. The polypeptide of claim 1 , wherein the modified B-H c is of strain 1.

8. The polypeptide of claim 2 wherein the protease domain, translocation domain, and protease cleavage site are from serotype selected from the group consisting of A, B, C, D, E, F, G, and combinations thereof.

9. The polypeptide of claim 8 , wherein the protease domain, translocation domain, and protease cleavage site are from serotype B, strain 1.

10. The polypeptide of claim 8 , wherein the protease domain, translocation domain, and protease cleavage site are from serotype A, strain 1.

11. A composition comprising a botulinum neurotoxin polypeptide comprising a modified receptor binding domain of Clostridial botulinum serotype B (B-H c ) comprising an amino acid substitution mutation at the amino acid position E1191 of the polypeptide of SEQ ID NO: 4 with M, Q, C, V, Y, T or I, wherein the substitution mutation produces enhanced binding of the modified B-H c to human SytII as compared to an identical molecule lacking the substitution mutation.

12. The composition of claim 11 , wherein the modified receptor binding domain of Clostridial botulinum serotype B (B-H c ) further comprises one or more amino acid substitution mutations at an amino acid position of the SEQ ID NO: 4, selected from the group consisting of:

substitution of E, H, Y, W, F, or L at S1199;

substitution of Q, Y, A or S at W1178;

substitution of C, P, or M at Y1183;

substitution of S, M or Y at P1117;

substitution of V at S1201;

substitution of M at V1118;

substitution of Y at A1196;

substitution of M at Y1181; and combinations thereof.

13. The composition of claim 11 , wherein the modified (B-H c ) comprises two substitution mutations.

14. The composition of claim 13 wherein the two substitution mutations correspond to:

E1191M and S1199Y;

E1191M and S1199W;

E1191M and S1199L;

E1191M and S1199Y;

E1191M and S1199F;

E1191Q and S1199Y;

E1191Q and S1199W;

E1191Q and S1199L;

E1191Q and S1199Y;

E1191Q and S1199F;

E1191C and S1199Y;

E1191C and S1199W;

E1191V and S1199Y;

E1191V and S1199W;

E1191M and W1178Q;

E1191Q and W1178Q;

E1191C and W1178Q; or

E1191V and W1178Q.

15. A kit comprising a composition comprising a botulinum neurotoxin polypeptide comprising a modified receptor binding domain of Clostridial botulinum serotype B (B-H c ) comprising an amino acid substitution mutation at the amino acid position E1191 of the polypeptide of SEQ ID NO: 4 with M, Q, C, V, Y, T or I, wherein the substitution mutation produces enhanced binding of the modified B-H c to human SytII as compared to an identical molecule lacking the substitution mutation, and directions for therapeutic administration of the composition.

16. A chimeric molecule comprising a first portion that is the modified receptor binding domain of Clostridial botulinum serotype B (B-Hc) comprising an amino acid substitution mutation at the amino acid position E1191 of the polypeptide of SEQ ID NO: 4 with M, Q, C, V, Y, T or I linked to a second portion.

17. A composition comprising chimeric molecule comprising a first portion that is the modified receptor binding domain of Clostridial botulinum serotype B (B-Hc) comprising an amino acid substitution mutation at the amino acid position E1191 of the polypeptide of SEQ ID NO: 4 with M, Q, C, V, Y, T or I linked to a second portion.

18. A kit comprising a composition comprising chimeric molecule comprising a first portion that is the modified receptor binding domain of Clostridial botulinum serotype B (B-Hc) comprising an amino acid substitution mutation at the amino acid position E1191 of the polypeptide of SEQ ID NO: 4 with M, Q, C, V, Y, T or I linked to a second portion and directions for administration of the composition.