Table 3.
Highly conserveda residues in the active site of PNGM enzymes and their potential functional roles
| Residueb | Proposed role (region) |
|---|---|
| Residueb3 | Proposed role (region) |
| R11 | General acid/base |
| T7 | Domain 1-to-4 latch |
| T414 | |
| S100 | Phosphoserine involved in phosphoryl transfer (i) |
| D240 | Metal-binding ligands (ii) |
| D242 | |
| D244 | |
| D308c | Specific/permissive for amino group at 2 position of sugar |
| M285c | |
| E325 | Sugar-binding loop (iii) |
| S327 | |
| R410 | Phosphate-binding site (iv) |
| S412 | |
| R419 |
a
All residues in this table are 100% conserved based on a multiple sequence alignment of 171 PNGM sequences (see the supplemental material).
b
Residue numbers refer to the BaPNGM protein.
c
Proposed role of D308 is specificity for binding glucosamine-6-P, while M285 appears to be permissive for binding glucosamine-1-P. The four conserved active site regions discussed in the text are indicated in parentheses.