TABLE 3.
Structural parameters of PG from dac mutant sporesa
| Genotype | % of muramic acid with side chain ofb:
|
% of Dpm in cross-links analyzed by:
|
||||
|---|---|---|---|---|---|---|
| Lactam | l-Ala | TP | TriP | HPLC | FDNB | |
| Wild type | 50c | 26 ± 1 | 23 ± 2 | 1.5 ± 0.1 | 13 ± 1 | 31 (1) |
| dacA | 49 ± 1 | 25 ± 4 | 25 ± 3 | 0.8 ± 0.2 | 12 ± 2 | 34 (1) |
| dacB | 47 ± 1 | 12 ± 1 | 43 ± 1 | 2.2 ± 0.1 | 36 ± 2 (30)d | 57 (1) |
| dacC | 51c | 26 ± 2 | 23 ± 3 | 1.4 ± 0.1 | 13 ± 3 | 31 (1) |
| dacF | 51 ± 1 | 28 ± 2 | 20 ± 2 | 1.4 ± 0.2 | 13 ± 1 | 30 (2) |
| dacA dacB | 46 ± 1 | 11 ± 2 | 47 ± 2 | 1.0 ± 0.1 | 37 ± 3 (28)d | 59 (2) |
| dacA dacC | 50c | 26 ± 3 | 24 ± 3 | 0.7 ± 0.1 | 14 ± 2 | 32 (2) |
| dacA dacF | 50 ± 1 | 26 ± 1 | 23 ± 2 | 0.9 ± 0.1 | 13 ± 1 | 31 (1) |
| dacB dacC | 46 ± 1 | 11 ± 1 | 45 ± 2 | 2.1 ± 0.2 | 36 ± 2 (28)d | 59 (2) |
| dacB dacFe | 40 ± 1 | 6 ± 4 | 57 ± 8 | 4.8 ± 0.4 | 33 ± 2 (23)d | 72 (4) |
| dacC dacF | 51c | 30 ± 1 | 18 ± 1 | 1.3c | 12 ± 1 | 32 (1) |
| dacA dacB dacC | 44 ± 2 | 12 ± 2 | 54 ± 4 | 1.8 ± 0.9 | 38 ± 3 (21)d | 60 (2) |
| dacA dacB dacFe | 42 ± 2 | 9 ± 3 | 54 ± 3 | 2.5 ± 0.3 | 26 ± 5 (15)d | 60 (2) |
| dacA dacC dacF | 51c | 29 ± 2 | 20 ± 2 | 0.7 ± 0.1 | 13 ± 3 | 29 (2) |
| dacB dacC dacFe | 39 ± 2 | 9 ± 4 | 52 ± 6 | 5.4 ± 0.6 | 34 ± 2 (27)d | 76 (2) |
Data are averages of analyses of 3 to 10 independent spore preparations (strain numbers as indicated in Table 2) with errors of 1 standard deviation except for cross-linking determinations using FDNB, for which the number of independent determinations is given in parentheses.
Abbreviations: Lactam, muramic-δ-lactam; TP, tetrapeptide; TriP, tripeptide.
These values showed no significant deviation among the samples assayed.
The values in parentheses are for effective cross-links; the remaining cross-links involve a peptide that has been cleaved from the muramic acid by a muramic acid-l-alanine amidase (1, 20, 21).
Values for all dacB dacF strains determined by HPLC analyses were calculated by using only identified peaks and ignoring the elevated baseline. Since the latter area undoubtedly includes a large amount of cross-linked muropeptides, the cross-linking values determined by HPLC are certainly underestimates.