TABLE 1.
Amino acid sequence homology of PQW, EAW, and HDS peptides with S. mutans, S. sobrinus, and S. downei GTFs and association with β5 and β7 strand domains
| Construct | Source (reference) | Sequencea | % Homology with peptide |
|---|---|---|---|
| PQW peptide | PQWNGESEKPYDDHL | ||
| GTF-B | S. mutans (18) | 342-SAWNSDSEKPFDDHL | 67 |
| GTF-C | S. mutans (29) | 368-SAWNSDSEKPFDDHL | 67 |
| GTF-D | S. mutans (10) | 354-PNWNSQTESDTSAGE | 27 |
| GTF-I | S. downei (6) | 342-PQWNGESEKPYDDHL | 100 |
| GTF-S | S. downei (8) | - - | 0 |
| GTF2 | S. sobrinus (1) | 336-PQWNGESEKPYDDHL | 100 |
| † # | |||
| EAW peptide | ANDHLSILEAWSDNDTPYLHD | ||
| GTF-B | S. mutans | 480-ANDHLSILEAWSDNDTPYLHD | 100 |
| GTF-C | S. mutans | 506-ANDHLSILEAWSYNDTPYLHD | 95 |
| GTF-D | S. mutans | 494-AINHLSILEAWSDNDPQYNKD | 68 |
| GTF-I | S. downei | 482-ANNHVSIVEAWSDNDTPYLHD | 90 |
| GTF-S | S. downei | 467-AIDHLSILEAWSGNDNDYVKQ | 63 |
| GTF2 | S. sobrinus | 476-ANNHVSIVEAWSDNDTPYLHD | 84 |
| . .β5. | |||
| ‡† ¤ | |||
| HDS peptide | VPSYSFIRAHDSEVQDLIA | ||
| GTF-B | S. mutans | 549-VPSYSFIRAHDSEVQDLIA | 100 |
| GTF-C | S. mutans | 575-VPSYSFIRAHDSEVQDLIRNII | 95 |
| GTF-D | S. mutans | 571-MANYIFIRAHDSEVQTVIAKII | 63 |
| GTF-I | S. downei | 551-VPSYSFARAHDSEVQDLIRDII | 84 |
| GTF-S | S. downei | 534-VPNYVFIRAHDSEVQTRIAKII | 74 |
| GTF2 | S. sobrinus | 545-VPSYSFARAHDSEVQDIIRDII | 84 |
| .β7. |
a
†, glutamic and aspartic acids at these positions are catalytic in α-amylases (14, 28); modification of these amino acids in GTF leads to loss of activity (5, 28). ‡, Histidine stabilizes transition states at this position in α-amylases (14, 22); modification of this histidine in GTF leads to loss of activity (28). #, Tryptophan is highly conserved at this position in GTF; activity is lost when mutated (28). ¤, Glucan product type changed when aspartic acid at this position in GTF is mutated (17).