TABLE 3.
Linkage analysis of the rgt mutant LPSs
PMAA were prepared from isolated LPS and analyzed by GC/MS to determine carbohydrate linkages. The relative abundance of Kdo residues having different linkages was estimated by selective ion monitoring for the diagnostic m/z 89 primary fragment ion derived from carbons 7 and 8 of each Kdo derivative. The relative abundance of Gal/GalA and Man residues was determined from the intensity of the shared m/z 118 primary ion. Numbers before each residue (i.e. 4-Kdo) represent the linked position. Derivatives and primary ion fragments: 6-linked Man, 1,5,6-tri-O-acetyl-2,3,4-tri-O-methyl-mannitol (m/z 118, 162, 189, 233); 4,6-linked Man, 1,4,5,6-tetra-O-acetyl-2,3-di-O-methyl-mannitol (m/z 118, 261); 6-linked Gal, 1,5,6-tri-O-acetyl-2,3,4-tri-O-methyl-galactitol (m/z 118, 162, 189, 233); T-GalA, 1,5,6-tri-O-acetyl-2,3,4-tri-O-methyl-6,6-2H-galactitol (m/z 118, 162, 191, 235); T-Kdo, 1,2,6-tri-O-acetyl-3-deoxy-4,5,7,8-tetra-O-methyl-1,1-2H-octitol (m/z 89, 146, 205, 206, 250, 366); 4,5-linked Kdo, 1,2,4,5,6-penta-O-acetyl-3-deoxy-7,8-di-O-methyl-1,1-2H-octitol (m/z 89, 186, 228, 348, 422); 4-linked Kdo, 1,2,4,6-tetra-O-acetyl-3-deoxy-5,7,8-tri-O-methyl-1,1-2H-octitol (m/z 89, 205, 278, 320, 394).
| Strains | 89 m/z ion extraction |
118 m/z ion extraction |
|||||
|---|---|---|---|---|---|---|---|
| T-Kdo | 4-Kdo | 5-Kdo | 4,5-Kdo | 6-Gal (T-GalA)a | 6-Man | 4,6-Man | |
| 3841 (Parent Strain) | 9.8 | 28 | 0.0 | 62 | 77 | 0.0 | 23 |
| EL202 (rgtE−) | 49 | 15 | 0.0 | 36 | 51 | 49 | 0.0 |
| EL203 (rgtA−) | 45 | 24 | 0.0 | 31 | 66 | 14 | 20 |
| EL204 (rgtB−) | 6.2 | 63 | 0.0 | 31 | 66 | 2.9 | 31 |
| EL205 (rgtC−) | 16 | 22 | 0.0 | 62 | 77 | 18 | 4.4 |
| EL206 (rgtD−) | 20 | 43 | 0.0 | 36 | 67 | 18 | 15 |
a 6-linked Gal and terminal GalA can be distinguished by the relative abundance of ions m/z 189/191 and m/z 233/235. T, terminally linked residue.